It is narrated from the Mother of the Believers, Sayyidah Aishah (may Allah be pleased with her), that she said: "I heard the Messenger of Allah (peace and blessings be upon him) saying: 'O Allah, whoever is put in charge of any affair of my Ummah and is gentle with my Ummah, then be gentle with him; and whoever is harsh with them, then be harsh with him.'"
No one narrated this hadith from Amr bin al-Harith (may Allah have mercy on him) except Ibn Lahi'ah (may Allah have mercy on him), and the name of Abu Ali al-Hamdani (may Allah have mercy on him) is Thumamah bin Shufayy (may Allah have mercy on him).
Hadith Referenceالمعجم الأوسط / باب الألف / 360
Hadith Takhrij«أخرجه مسلم فى «صحيحه» برقم: 1828، وابن حبان فى «صحيحه» برقم: 553، والنسائي فى «السنن الكبرى» برقم: 8822، والبيهقي فى «السنن الكبرى» برقم: 17986، 17987، 20529، وأحمد فى «مسنده» برقم: 24975، 25261، 26840، 26853، 26878، والطبراني فى «الأوسط» برقم: 6915، 9449»