Zayd bin Aslam narrates: Sayyiduna Umar (may Allah be pleased with him) said concerning those six people, with whom the Prophet (peace and blessings be upon him) was pleased when he departed from this world: "Pledge allegiance to the one to whom Abd al-Rahman bin Awf (may Allah be pleased with him) pledges allegiance; if anyone refuses, strike off his neck."
(Allamah al-Haythami says:) I say: The opening part of this narration is reported in the Sahih.
Al-Tabarani recorded it in al-Mu'jam al-Awsat. The narrator Zayd did not live in the time of Sayyiduna Umar (may Allah be pleased with him); his son Abdullah was declared thiqah (trustworthy) by Ma'n bin Isa and others, while the majority declared him da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الخلافة / 8944