Nafi' narrates from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that a woman of the Ansar went to her husband's slave woman and nursed her. When her husband came, she said: This slave woman of yours has become your daughter. He went to Sayyiduna Umar (may Allah be pleased with him) and mentioned this matter to him. Sayyiduna Umar (may Allah be pleased with him) said to him: I firmly instruct you that when you return, you are to have relations with your slave woman and to punish your wife on her back.
In the narration of Abdullah bin Dinar it says: Fosterage is (only) that of a young child.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرضاع / 15660