Sayyiduna Abdullah bin Abi Awfa (may Allah be pleased with him) narrates: One day the Prophet (peace and blessings be upon him) was going out, and on the way he saw a child who was crying. The Prophet (peace and blessings be upon him) said: 'O Umar! Take hold of this child, for he is lost.' Meanwhile the child's mother came and took the child. She clasped the child to herself and began kissing him while rocking him, and weeping. The Prophet (peace and blessings be upon him) asked: 'Do you think that she is merciful towards her child?' The people replied: 'Yes!' The Prophet (peace and blessings be upon him) said: "By Allah! Allah Almighty is more merciful to the Muslims than this woman is (merciful) to her child."
At-Tabarani recorded it; its chain contains a narrator, Fa'id Abu al-Warqa', who is matruk (abandoned). A hadith narrated from Sayyiduna Umar (may Allah be pleased with him) will come at the end of the book relating to the Resurrection.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب التوبة / 17610