It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) would supplicate after the prayer: "'Allahumma inni as'aluka rizqan tayyiban wa 'amalan mutaqabbalan wa 'ilman nafi'an' (O Allah, I ask You for pure provision, accepted deeds and beneficial knowledge)."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19989