Judgment B. R. Singh, J. 1. The petitioners herein are aggrieved by the Resolution of the respondent-Municipal Corporation dated 20th October, 1986 (Annexure-2)being Resolution Nos.96 and 97) whereby it was decided to promote respondent No.4 to the post of Upper division Tax Collector on the ground that he had the requisite educational qualification, being a graduate. The petitioners, who are senior to him, have been overlooked on the ground that they do not have the necessary educational qualification for promotion to the post of Upper Division Tax Collector. Annexure-3, a formal order granting promotion to respondent No.4, is dated 22-11-1986. Annexure-4 is the consequential order fixing the pay of respondent No.4. 2. The facts of the case are not in dispute. The petitioners herein were appointed as Tax Collector. Petitioner No.1, being the seniormost, was appointed on 17-10-1947 while petitioner No.5, the juniormost amongst them, was appointed as Tax Collector on 17-8-1959. Resondent No.4, who happened to be a graduate, was also appointed as Tax collector on 16-6-1962. Having regard to his length of service, it is not disputed that as Tax Collector he was junior to the petitioners; 3. From Annexure-1 it appears that the respondent-Municipal Corporation took a decision to fill up the post of upper Division Tax Collector by promotion. Pursuant to the said decision the Resolution (annexure-2)was passed, which was followed by the impugned order of promotion 9 (Annexure-3 ). 4. The grievance of the petitioners is that they being senior to respondent no.4, they could not be superseded unless they were found to be unfit for promotion. According to them, the rule applicable in the case of promotion to the post of Upper Division Tax collector is seniority, subject to weeding out those found unfit. According to them, there is no requirement of the promotee being a graduate, or holding a higher degree. All Tax Collectors are eligible for promotion to the post of Upper division Tax Collector. 5. On the other hand, the case of the respondent-corporation as well as respondent No.4 appears to be that for promotion to the post of Upper division Tax Collector the candidate must be at least a graduate. 6. All Tax Collectors are eligible for promotion to the post of Upper division Tax Collector. 5. On the other hand, the case of the respondent-corporation as well as respondent No.4 appears to be that for promotion to the post of Upper division Tax Collector the candidate must be at least a graduate. 6. The respondents relied upon a decision take in the year 1953 by an executive Officer, who while advertising the post of Upper Division Tax collector to be filled up by direct recruitment prescribed that the candidates must at least be a graduate. One of the Upper division Tax Collectors so appointed retired in the year 1985, and as a result of the vacancy caused by his superannuation, the impugned decision was taken by the Municipal Corporation to fill up that post by promotion, Rule 540 of the Patna Municipal Corporation act, 1951, vests power in the State government to make rules for the purpose of carrying into effect the provisions of the Act. Rules have been framed by the State Government, which are known as the Patna Municipal corporation Officers and Servants (Appointment, Duties, Discipline and appeal) Rules, 1955. Rule 4 provides that all vacancies whether permanent or temporary, the duration of which exceeds a month, and which are not filled up by promotion from among the officers or servants of the Corporation or by the appointment of a probationer already in the pay and service of the corporation, shall be duly advertised in at least two consecutive issues of a newspaper having wide circulation within the limits of the State. Rule 6, on the other hand, provides as follows: "6. Promotion of an officer or servant of the Corporation to a higher post shall ordinarily be made according to seniority and no officer or servant of the corporation shall be passed over unless, for reason to be recorded in writing, the Chief executive Officer or the Standing Committee or the Corporation, as the case may be, consider him to be unfit for promotion. " 7. It wound thus appear that the procedure prescribed under Rule 4 has to be followed in the case of direct recruitment, and where it is decided not to fill up the post by promotion. " 7. It wound thus appear that the procedure prescribed under Rule 4 has to be followed in the case of direct recruitment, and where it is decided not to fill up the post by promotion. Counsel for the Corporation, therefore, sub-mitted that the procedure under Rule 4 has not been followed because this was a case of promotion, and not a case of direct recruitment. The express words of rule 6 are to the effect that promotion of an officer or servant of the corporation to a higher post shall ordinarily be made according to seniority. It further prohibits the Corporation from passing over any officer or servant unless, for reasons to be recorded in writing, the chief Executive Officer of the Standing committee or the Corporation, as the case may be, consider him to be unfit for promotion. It is well-settled rule of interpretation that a prohibitory provision is considered to be mandatory and, therefore, while Rule 6 commands that in the matter of promotion seniority shall be the guiding factor, an exception is carved out only in cases the concerned candidate is considered to be unfit by the appointing authority. The rule does not merey say so, but further casts an obligation on the appointing authority to record its reasons in writing. As I read Rule 6, in the matter of promotion, no additional qualification is prescribed and the Rule prescribed for the appointment of seniormost officer, subject to weeding out those found unfit In the instant case, it is not the case of the Corporation that the petitioners have been found to be unfit. The Resolution says that they did not possess the requisite educational qualification. In my view, the resolution of the Corporation proceeds on an erroneous assumption that any higher qualification has been laid down for promotion to the post of Upper Division Tax Collector. 8. Reliance upon an executive decision of the Chief Executive Officer of the year 1953 is also misconceived. That decision was taken at a time when the Rules had not been framed. Moreover, that decision was taken in connection with filling up the post by direct recruitment, and not by promotion. 8. Reliance upon an executive decision of the Chief Executive Officer of the year 1953 is also misconceived. That decision was taken at a time when the Rules had not been framed. Moreover, that decision was taken in connection with filling up the post by direct recruitment, and not by promotion. It is well settled that even in absence of rules, executive instructions may be issued from time to time to cover the field normally covered by the rules, subject to such instructions not being violative of Articles 14 and 16 of the Constitution of India. However, it is equally well settled by a catena of decisions that once the statutory rules are framed by the competent authority, those rules must prevail over any earlier executive decision. The Rules having been framed in the year 1955, supersede all earlier executive decisions and, therefore, any promotion which is to be granted must be granted strictly in accordance with the rules. In the instant case, rule 6 applies and, therefore, the seniormost Tax Collector, who is not found to be unfit, ought to be promoted to the post of Upper Division Tax collector. The respondents have clearly erred in law by laving down an additional educational qualification, contrary to the rules, which prescribe the rule of seniority subject to weeding out the unfit. 9. Mr. S. P. Mukharjee, Counsel appearing on behalf of respondent No.4, submitted that respondent No.4 being a graduate may be preferred as against the petitioners, who are not graduates. If the rules made such a provision, the rule could not be held to be bad, but the rules do not so provide. In the matter of promotion, the promoting authority has to be solely guided by the principle laid down in the said Rule, namely, seniority, subject to rejection of the unfit. 10. In these circumstances, this writ petition is allowed and Annexures 2 and 3 are quashed. Annexure-4, being consequential in nature is also quashed; but the respondent-Corporation will not recover from respondent No.4 the additional pay, if any, which may have been paid to him during the period he has worked as Upper Division Tax collector pursuant to the impugned orders. The respondent-Corporation is hereby directed to reconsider the matter regarding promotion strictly in accordance with Rule 6 of the Rules, and in the light of the observations contained in this judgment. The respondent-Corporation is hereby directed to reconsider the matter regarding promotion strictly in accordance with Rule 6 of the Rules, and in the light of the observations contained in this judgment. There will be no order as to costs. I am informed that petitioner No.1 has already retired from service, and other persons, who are working for a long time, are nearing the age of retirement. In these circumstances, the Municipal corporation is directed to take a final decision in the matter within three months from today. Petition Allowed.