On the authority of Abu Hurayrah (may Allah be pleased with him), who said that the Messenger of Allah (peace and blessings of Allah be upon him) said:

"Allah (glorified and exalted be He) said:

'I am so self-sufficient that I am in no need of having an associate. Thus he who does an action for someone else's sake as well as Mine will have that action renounced by Me to him whom he associated with Me."

[Muslim (also by Ibn Majah).]