Was the meeting of Imam Abu Hanifa and Imam Malik during Hajj about issues of consensus (Ijma'), analogical reasoning (Qiyas), or custom (Urf), and who said that the legal rules for every issue should not be acted upon and that delving into them is forbidden by Sharia?

The story of the meeting between Imam Abu Hanifa and Imam Malik has not been found. It is well-known that consensus (Ijma') takes precedence over analogical reasoning (Qiyas) and custom (Urf). As for custom, it takes precedence over analogical reasoning if it is sound (i.e., does not permit what is forbidden nor forbid what is permitted). However, analogical reasoning does not take precedence over corrupt custom. There is nothing to indicate a prohibition against delving into principles upon which no practical action is built. Indeed, some books on Usul (principles of Islamic jurisprudence) have mentioned issues "upon which no practical action is built."