Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.089.

Ibn al-Qayyim said, “Some of the latter jurists hold it desirable while others do not agree because they regard it as an innovation (bid’ah). The Companions never did it. The Prophet, peace be upon him, shall receive a reward for every good done by anyone from among his community (Ummah) without in the least diminishing the reward of the doer. This is because he is the one who invited his community to every good, and led them to it, and because the one who calls others to truth always has a reward similar to that of those who follow it without in any way diminishing their reward. Whatever guidance or knowledge his community gained, they gained it only through him, so he shall have a reward equal to that of his followers whether they formally dedicate it to him or not.