Some scholars may place their hands by their sides and others may place their hands on their chests during Salah. Those who place their hands by their sides do not pray behind those who place their hands on their chests and vice versa.
Please, give us the legal decision in this regard!
It has been authentically reported that the Prophet (peace be upon him) used to place his right hand over his left whether offering an obligatory or supererogatory prayer.
This is the view of the Jumhur (dominant majority) of scholars which is the soundest view. However, Malik disapproved of it with regard to the obligatory prayer lest a person may lean on his hands placed against his body, and he allowed it in the supererogatory prayer.
Abu Al-Walid Muhammad ibn Ahmad ibn Rushd mentioned in his book, "Al-Muqadimah", that placing the hands over each other on the chest is a desirable act of Salah. He added that
Malik disapproved of it to be considered an obligatory act of Salah. According to the views of the scholars, it is permissible for people who place their hands on their chest to pray behind those who place their hands to their sides.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.