Muwatta Imam Malik Book of Divorce, Hadith 16
Yahya related to me from Malik that he had heard that Abdullah ibn Umar and Abu Hurayra were asked about a man who gave his wife power over herself, and she returned it to him without doing anything with it. They said that there was no divorce. (i.e. The man's giving his wife power over herself was not interpreted as a desire for divorce on his part.)
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، وَأَبَا، هُرَيْرَةَ سُئِلاَ عَنِ الرَّجُلِ، يُمَلِّكُ امْرَأَتَهُ أَمْرَهَا فَتَرُدُّ ذَلِكَ إِلَيْهِ وَلاَ تَقْضِي فِيهِ شَيْئًا فَقَالاَ لَيْسَ ذَلِكَ بِطَلاَقٍ .