Abu Uthman al-Nahdi (may Allah have mercy on him) says: Sayyiduna Umar (may Allah be pleased with him) assigned a man from Banu Asad to a post. He came to collect his letter of appointment, and at that time one of the children of Sayyiduna Umar (may Allah be pleased with him) was brought to him and he kissed him. The man said: "Do you kiss him? I have never kissed any child." Sayyiduna Umar (may Allah be pleased with him) said: "Then you have little mercy towards people. Give back our letter of appointment, and never work for us again."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17906