Is supplicating for the deceased before their burial a bid‘ah, or what is it?

Supplicating for the deceased is a Sunnah both before and after burial. It has been authentically reported that the Prophet, peace and blessings be upon him, supplicated for Abu Salamah after his death and before his burial. The angels say "Amin" to what is said. It is recommended to supplicate for the deceased when closing their eyes and softening their joints.