(a) It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) was standing delivering the Friday sermon when suddenly a man from the first Muhajirun came. Sayyiduna Umar (may Allah be pleased with him) called out to him: "What time is this?" He said: "Today I was busy and could not go home; when I heard the call to prayer, I could do nothing more than perform ablution." Sayyiduna Umar (may Allah be pleased with him) said: "Only ablution? And yet you know that the Messenger of Allah (peace and blessings be upon him) used to order the ritual bath." (b) Imam Bukhari (may Allah have mercy on him) narrated this report from Abdullah bin Asma'. Imam Malik (may Allah have mercy on him) recorded it in the Muwatta as mursal and did not mention Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) in the chain. Outside the Muwatta it has been narrated as connected (mawsul), and that is what is correct. It is also reported as connected from Imam al-Zuhri (may Allah have mercy on him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1404