Grading: This hadith is "sahih li-ghayrihi" (authentic due to supporting evidence).
Technical note / Defect ('illah): This chain is "hasan" in corroborating chains and supporting reports because it contains Abd Allah bin Salih (the scribe of al-Layth bin Sa'd). A similar narration is reported from Abd Allah bin Umar bin al-Khattab with a sahih chain.

Reference / Source: Al-Tabarani narrated it in "al-Mu'jam al-Kabir" (7287) via Muttalib bin Shu'ayb, from Abd Allah bin Salih, with this same chain.

Reference / Source: Within the lengthy report of Umar bin al-Khattab's stabbing and death, it was narrated by al-Tabari in his "Tarikh" (4/ 190-193) and al-Ajurri in "al-Shari'ah" (1399) by way of Abd al-Aziz bin Abi Thabit al-Zuhri, from Abd Allah bin Ja'far al-Makhrami, from his father, from al-Miswar bin Makhramah.
Technical note / Defect ('illah): Abd al-Aziz is "matruk al-hadith" (abandoned in hadith), and Ja'far, the father of Abd Allah, is not known.

Important point: However, Umar bin al-Khattab's order, after he was stabbed, that Suhayb (may Allah be pleased with him) should lead the people in prayer is authentically established from the hadith of Abd Allah bin Umar, found in Abd al-Razzaq (9776) and Umar bin Shabbah's "Tarikh al-Madinah" (3/ 924) by two sahih routes from Ibn Umar.