Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) reports that the Prophet (peace and blessings be upon him) said: "Sometimes a man earns wealth in a lawful way and eats from it himself; likewise a man has wealth in which charity is due; then that person recites:
'Allahumma salli 'ala Muhammadin 'abdika wa rasulika, wa salli 'alal-mu'minina wal-mu'minat, wal-muslimina wal-muslimat' (O Allah, send blessings upon Sayyiduna Muhammad (peace and blessings be upon him), who is Your servant and Your Messenger, and send mercy upon the believing men and the believing women, and the Muslim men and the Muslim women).
(The Prophet (peace and blessings be upon him) said:) Then this will become a means of purification for him."
Abu Ya'la recorded it, and its chain is hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأدعية / 17321