The ruling on one who prays sitting behind the imam without an excuse

Question:
I was praying behind an imam, then my child cried very loudly, which disturbed the worshippers. This forced me to pray two units of the prayer sitting down. After the prayer ended, one of the worshippers advised me to repeat the prayer because I had contradicted the imam. Is this correct?

Answer:
Yes, if a person sits during the obligatory prayer while he is able to stand, his prayer is invalid, so you must repeat it. If the child screams, let him scream, and praise be to Allah, there is no blame on you.