Sayyiduna Abu Umamah (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Take on as much (voluntary) worship as you are able to, for Allah Almighty does not grow weary; rather, you grow weary."
This narration was recorded by Imam al-Tabarani in al-Mu'jam al-Kabir; its chain contains a narrator, Bishr bin Numayr, who is "da'if" (weak).