Mohammad bin Abu bakar is the son of Ali

Ali Called Muhammad ibn Abi Bakr His Son

Sharh Nahj al-Balagha v6 p53
Muhammad ibn Abi Bakr was raised by Ali and was treated like one of his own children, until Ali said: “Muhammad is my son, from the loins of Abu Bakr.”
وكان محمد ربيبه وخريجه، وجارياً عنده مجرى أولاده ... حتى قال علي عليه السلام: محمد ابني من صلب أبي بكر

See also

• Mawla Ali is leader and higher and above than every sahaba and prophet except prophet Mohammad
• Mawla Ali is the successor of prophet Mohammad
• Mohammad bin Abu bakar role in killing uthman
• Look at Ali face is ibadat (worship)