Sahih Muslim Book 32, Hadith Number 6290.

Chapter : He upon whom Allah’s Apostle (may peace be upon him) invoked curse whereas he in fact did not deserve it, it would be a source of reward and mercy for him.

Abu Huraira reported Allah’s Apostle (may peace be upon him) as saying: O Allah, I make a covenant with Thee against which Thou wouldst never go. I am a human being and thus for a Muslim whom I give any harm or whom I scold or upon whom I invoke curse or whom I beat, make this a source of blessing, purification and nearness to Thee on the Day of Resurrection.