Sayyidah Aishah (may Allah be pleased with her) narrates from Umm Salamah (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) came to me after Asr and prayed two rak'ahs. Umm Salamah (may Allah be pleased with her) said: I said: O Messenger of Allah, what are these two rak'ahs? You did not used to pray them. He (peace and blessings be upon him) said: "I used to pray them after Zuhr. One day some wealth came to me, and being busy distributing it, I could not pray the two rak'ahs. I have prayed them now."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4561