Majma al-Zawaid — Hadith 685

Sayyiduna Umar (may Allah be pleased with him) said: A letter came to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said to Sayyiduna Abdullah bin al-Arqam (may Allah be pleased with him): "Reply to those people." Sayyiduna Abdullah bin al-Arqam (may Allah be pleased with him) took the letter and wrote its reply, then brought the writing to read it out to the Prophet (peace and blessings be upon him), and the Prophet (peace and blessings be upon him) said: "You have done well." Sayyiduna Umar (may Allah be pleased with him) says: This incident stayed in my mind, until, when I became Caliph, I appointed him (that is, Sayyiduna Abdullah bin al-Arqam (may Allah be pleased with him)) in charge of the treasury (bayt al-mal).
Al-Bazzar recorded it; its chain contains a narrator, Muhammad bin Sadaqah al-Fadaki, and the author of "al-Mizan" (that is, Mizan al-I'tidal) stated: "His hadith is munkar (denounced)."