Aslam, the freed slave of Umar (may Allah have mercy on him), relates that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) went out to the mosque of the Messenger of Allah (peace and blessings be upon him) and found Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) weeping beside the grave of the Messenger of Allah (peace and blessings be upon him). He asked: What makes you weep, O Mu'adh? He said: What makes me weep is something I heard from the occupant of this grave. He asked: And what is it? He said: I heard him say: "Even a little showing off is shirk (associating partners with Allah), and whoever shows enmity to the friends of Allah has initiated war against Allah. Indeed, Allah, the Mighty and Majestic, loves the hidden, God-fearing ones who, when absent, are not missed, and when present, are neither invited nor recognised. Their hearts are lamps of guidance; they emerge from every dark and dusty (trial)."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17457
Aslam, the freed slave of Umar (may Allah have mercy on him), relates that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) went out to the mosque one day and found Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) weeping beside the grave of the Messenger of Allah (peace and blessings be upon him). Then the narrator mentioned a similar hadith.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17458