Why Imam at-Tahawi left Shafiee Madhab and accepted Hanafi Madhab.
Ibn Kathir said:
at-Tahawi left Shafiee madhab because his uncle, al Muzni (student of Imam ash-Shafiee) said to him in anger:
والله لا يجيء منك شيء.
By Allah, Nothing will come from you.
At-Tahawi became angry and left him (as a teacher) and became student of Abi Jafar Bin abi Imran al Hanafi and became so worthy that he excelled from all the scholars of his era. (al Bidaya wal Nihaya the year 321 h)
Note:
Imam atTahawi had an argument with Qadhi Abu Obaid, atTahawi said
فقلت له أيها القاضي أو كل ما قاله أبو حنيفة أقول به فقال ما ظننتك إلا مقلدا فقلت له وهل يقلد إلا عصي فقال لي أو غبي
I said: What (do you think that) each and every saying of Abu Haneefa is my saying? He (Qadhi abu Obaid) said: I consider you a muqallid (at Tahawi replied) The one who makes taqleed is stubborn or he has a memory problem [Lisan al Meezan vol 1 page 280 Shamela, in the Tarjuma of Imam at-Tahawi no. 836]