It was only his intuition.

It was only his intuition. ‘Umar, on his part, completely refrained from offering any Salat as long as he could not find water. Both recounted their experiences to the Messenger of Allah, sallallahu ‘alaihi wa alihi , who taught them tayammum as the correct step should they encounter a similar situation. During ‘Umar’s rule, a man came to him with the same problem that he personally had gone through.

But, rather than offer to him the solution of tayammum as taught by the Prophet, ‘Umar instructed the man with his own initial wrong step! ‘Ammar attempted to remind ‘Umar of the Sunnah in such situations. But, the latter simply did not want to hear about it! There are a number of questions here. First and foremost, did ‘Umar deliberately reject the Sunnah or not? This depends upon whether he actually remembered the incident involving him and ‘Ammar.

If he did, and still gave the ruling that he gave, then he would have been contemptuous of the Sunnah. Moreover, even if he had completely forgotten it, why did he not act on ‘Ammar’s reminder? From the look of it, he was not convinced by ‘Ammar’s narration. He most probably had very serious doubts about the accuracy of ‘Ammar’s hadith . Therefore, he saw no real reason to alter his decision on the matter.

So, the best-case scenario is that ‘Umar had absolutely forgotten the incident of tayammum , which involved him personally and directly. In addition, when ‘Ammar attempted to revive his memory of the event, he had grave trust issues with the latter’s report. Therefore, he did not remember, and there was no other reliable source to bring back his memories of the incident. The worst-case scenario is that ‘Umar actually remembered the hadith , or was at least successfully reminded of it by ‘Ammar.

Yet, he thought that his personal solution to the issue before him outweighed the Sunnah of the Messenger of Allah. As such, he was in contempt of Muhammad and his teachings. We will go with the best-case scenario. ‘Umar had completely forgotten, and was not successfully reminded. This fact casts a mammoth shadow of doubt over ‘Umar’s memory power.

Since he forgot the incident of tayammum so completely and absolutely, it is extremely uncertain that he was able to remember many – if not most - other teachings of the Prophet that were necessary in his discharge of his day-to-day judicial functions. The end result is that he lacked the requisite scholarly prowess for the office.