From Sahih Muslim (Hadith 2572):
A'isha (Allah be pleased with her) said:The Apostle of Allah (ﷺ) forbade them (his Companions) to observe Saum Wisal out of mercy for them. They said: You (Holy Prophet) yourself observe it. Upon this he said: I am not like you. My Lord feeds me and provides me drink
Reference: Muslim 2572