Abdullah bin Uthman bin Khuthaym narrates: I visited Sayyiduna Abu al-Tufayl Amir bin Wathilah (may Allah be pleased with him) and found him in a cheerful mood. I said: "O Sayyiduna Abu al-Tufayl (may Allah be pleased with him), tell me about the people whom the Messenger of Allah (peace and blessings be upon him) cursed." He was about to tell me about them when his wife, Sayyidah Sawdah (may Allah be pleased with her), said: "O Abu al-Tufayl, stop! Has it not reached you that the Prophet (peace and blessings be upon him) said: 'O Allah, I am a human being; whichever person among the believers I supplicate against, make it for him a means of purification and mercy'?"
Al-Tabarani recorded it in al-Mu'jam al-Awsat, and the wording of the narration is his; Ahmad recorded something similar, and his chain is hasan (good).