صحيح الادب المفرد
Sahih al-Adab al-Mufrad
Part One: Ahadith 1 to 249
باب من لا يرحم لا يرحم
Who does not show mercy will not be shown mercy
Hadith Number: 72
72/99 عن ابي عثمان ؛ ان عمر رضي الله عنه استعمل رجلا، فقال العامل: إن لي كذا وكذا، الولد، ما قبلت واحدا منهم! فزعم عمر، او قال عمر:" إن الله عز وجل لا يرحم من عباده إلا ابرهم".
It is narrated from Abu Uthman that Sayyiduna Umar (may Allah be pleased with him) appointed a man as an official. The official said: I have so many sons, but I have not kissed any of them. So Sayyiduna Umar (may Allah be pleased with him) thought, or Umar said: Allah, the Mighty and Majestic, only shows mercy to those among His servants who are the best in their conduct towards others.
تخریج الحدیث: (حسن الإسناد)