Grading: (3) It is "hasan li-ghayrihi" (sound due to supporting reports), in sha' Allah. Abd Allah bin Salih (the scribe of al-Layth) is acceptable in corroborating chains and supporting reports.
Technical note / Defect ('illah): However, there is disagreement over him as to whether this chain is connected or mursal. Al-Fadl bin Muhammad al-Bayhaqi narrated it from him in connected form with the author (al-Hakim), and from the author al-Bayhaqi narrated it in "al-Sunan al-Kubra" (10/ 126).

Technical note / Defect ('illah): Al-Fadl bin Muhammad was contradicted by al-Muttalib bin Shu'ayb al-Azdi, in al-Tabarani's "al-Kabir" (15035); he narrated it from Abd Allah bin Salih, from Abd al-Aziz bin Abi Salamah al-Majishun, from Abd al-Wahid bin Abi 'Awn, in mursal form.

Grading: However, this report is also narrated through another route, over whose connection or mursal status there is likewise disagreement; nevertheless, by the combination of these two narrations the report can be strengthened.

Reference / Source: It was recorded by al-Bazzar (267), Abu al-Qasim al-Baghawi in "Mu'jam al-Sahabah" (1521) and Hamzah bin Yusuf al-Sahmi in "Tarikh Jurjan" (p. 455) through the route of Muhammad bin Sadaqah al-Fadaki, from Malik, from Zayd bin Aslam, from his father, who said: Umar said: A letter came to the Prophet (peace and blessings be upon him), so he said to Abd Allah bin al-Arqam al-Zuhri: "Write them a reply." He wrote the reply and showed it to the Prophet (peace and blessings be upon him), and he said: "You have written correctly." Umar said: I said (to myself): The Messenger of Allah (peace and blessings be upon him) was pleased with what he wrote. This stayed in my mind until, when Umar became caliph, he put him in charge of the treasury (bayt al-mal).
Technical note / Defect ('illah): Al-Daraqutni said in "al-'Ilal" (168): Muhammad bin Sadaqah al-Fadaki is alone in narrating this hadith - he is not well known, but there is no harm in him - he narrates it from Malik, from Zayd, from his father, from Umar, while others narrate it from Malik in mursal form.

Note / Clarification: We say: that is, as Ishaq bin Muhammad al-Farwi narrated it from Malik, from Zayd bin Aslam, from Umar, without mentioning Aslam the freed slave of Umar. Abu Tahir al-Silafi likewise recorded it in "al-Mashyakhah al-Baghdadiyyah" (39). Ishaq has some weakness, but he is acceptable (in supporting reports).

Technical note / Defect ('illah): Or al-Daraqutni may have meant by "mursal" that it is narrated from Malik as a "balagh" (an unattributed report: "it reached me"), as Mutarrif bin Abd Allah al-Yasari narrated it in Ibn Sa'd (6/ 73), and Abd al-Rahman bin al-Qasim (as Ibn Abd al-Barr pointed out in "al-Isti'ab", p. 381). Both of them narrate from Malik, saying: "It reached me that a letter came to the Messenger of Allah (peace and blessings be upon him)..." (1) Likewise it was narrated by Abd Allah bin al-Zubayr [Ibn 'Asakir 4/ 336], al-Miswar bin Makhramah [Ibn Sa'd 6/ 73], and Zayd bin Aslam in mursal form [Khalifah's "Tarikh", p. 156]. Al-Zuhri also narrated in mursal form [Abd al-Razzaq 7723, Ibn Abi Shaybah 3/ 184, Abu Zur'ah p. 419, Ibn Khuzaymah 1100] that Abd Allah bin al-Arqam and Abd al-Rahman bin Abd al-Qari were in charge of the treasury in the time of Umar; and al-Zuhri also narrated, in al-Baladhuri's "Ansab al-Ashraf", a story indicating that Abd Allah bin al-Arqam was in charge of the treasury at the beginning of Uthman's caliphate as well.

Technical note / Defect ('illah): It is not stated in any of the narrations that Abd Allah bin Arqam remained in charge of the treasury in the time of Uthman until his death, as al-Zubayr bin Bakkar asserted categorically here. Rather, what comes in most of them is that Abd Allah bin al-Arqam asked Uthman to relieve him of the treasury, so Uthman relieved him (accepted his resignation) and after him handed the keys of the treasury to Zayd bin Thabit (may Allah be pleased with him).