Hadithcore
Sahih al-Bukhari, 5290
sahih

Narrated Nafi`:

Ibn `Umar used to say about the Ila (which Allah defined (in the Holy Book), "If the period of Ila expires, then the husband has either to retain his wife in a handsome manner or to divorce her as Allah has ordered."

حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا اللَّيْثُ، عَنْ نَافِعٍ، أَنَّ ابْنَ عُمَرَ، رضى الله عنهما كَانَ يَقُولُ فِي الإِيلاَءِ الَّذِي سَمَّى اللَّهُ لاَ يَحِلُّ لأَحَدٍ بَعْدَ الأَجَلِ إِلاَّ أَنْ يُمْسِكَ بِالْمَعْرُوفِ، أَوْ يَعْزِمَ بِالطَّلاَقِ، كَمَا أَمَرَ اللَّهُ عَزَّ وَجَلَّ‏.‏

References2 variants
In-Book Reference
Book 68, Hadith 39
USC-MSA web (English) reference
Vol. 7, Book 63, Hadith 213 (deprecated numbering scheme)