Assalamu alaikum. I was praying Asr in jama'ah in a shopping mall in a Muslim country which is predominantly Shafi'i. After the 2nd rakah, the imam sat but forgot to recite the Tashahud. He stood right up and despite people saying, "Subhanallah", he carried on with the third rak'ah and completed the prayer. I assumed he would do the sujud as-sahu before his salam but he did not do it either before or after it and he left so I did the two prostrations alone by myself. I approached him after the salah and said he had left the tashahud; he said he realised but that the first tashahud is neither a rukn nor wajib so it was correct to follow him and there was no need to make sujud as-sahu. I found out afterwards that in the Shafi'i madhab, the first tashahud is not compulsory but, according to what I have learned and believe in, it is wajib and its ommission necessitates sujud as sahu. I would like to ask if I was right to do what I did and if not, what course of action would have been advisable? Jazakallah khair.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The first Tashahhud and sitting for it is only a recommended act according to the Shaafi'i and Maaliki Schools, and a Waajib (obligation) according to the Hanbali and Hanafi Schools. Therefore, according to the Shaafi'i School, whoever forgets the first Tashahhud, it is recommended from him to prostrate for forgetfulness, but it is not an obligation because the prostration for forgetfulness is recommended according to them and not an obligation.

Since you believe that the first Tashahhud is an obligation and you prostrated for forgetfulness after Tashahhud because you did not perform it, then your prayer is correct and you are not required to do anything.

For more benefit, please refer to Fataawa 81875 and 86560.

Allaah Knows best.