It is narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with him) that a woman disputed with her husband regarding her child. The Prophet Muhammad (peace and blessings be upon him) said: "The woman has more right to the child, as long as she does not marry (again)."
Hadith Referenceسلسله احاديث صحيحه / الزواج ، والعدل بين الزوجات وتربية الاولاد والعدل بينهم وتحسين اسمائهم / 1571