It is not permissible for a woman who has been thrice-divorced to return to the one who divorced her until she marries another husband who has intercourse with her, then divorces her, and she completes the 'Iddah
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا ابْنُ فُضَيْلٍ، ح وَحَدَّثَنَا أَبُو كُرَيْبٍ، حَدَّثَنَا أَبُو مُعَاوِيَةَ جَمِيعًا عَنْ هِشَامٍ، بِهَذَا الإِسْنَادِ .
A hadith like this has been narrated on the authority of Hisham with the same chain of transmitters.