Musnad Ahmad Hadith 12431

It is narrated from Anas bin Malik (may Allah be pleased with him) that once the Prophet (peace and blessings of Allah be upon him) entrusted a man to Hafsa bint Umar (may Allah be pleased with her) and said, "Watch over him." Hafsa (may Allah be pleased with her) became heedless, so the man slipped away. When the Prophet (peace and blessings of Allah be upon him) returned, he asked, "Hafsa! What happened to that man?" She said, "O Messenger of Allah (peace and blessings of Allah be upon him)! I became heedless and he ran away." The Prophet (peace and blessings of Allah be upon him) said, "May your hands be broken." After the Prophet (peace and blessings of Allah be upon him) left, she raised her hands. A little while later, the Prophet (peace and blessings of Allah be upon him) came again and asked, "Hafsa! What has happened to you?" She said, "O Messenger of Allah (peace and blessings of Allah be upon him)! You said such and such to me a little while ago." The Prophet (peace and blessings of Allah be upon him) said, "Lower your hands. I have made a supplication to Allah that if I ever invoke a curse upon anyone from my Ummah, He may make it a means of forgiveness for that person."