Narrated Mutarrif ibn Abdullah: Imran ibn Husayn was asked about a person who divorces his wife, and then has intercourse with her, but he does not call any witness to her divorce nor to her restoration. He said: You divorced against the sunnah and took her back against the sunnah. Call someone to bear witness to her divorce, and to her return in marriage, and do not repeat it.
Hadith Referenceسنن ابي داود / كتاب تفريع أبواب الطلاق / 2186
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:إسناده حسن, أخرجه ابن ماجه (2025 وسنده صحيح)
Benefits and Issues: In Surah At-Talaq it is stated: (فَإِذَابَلَغْنَأَجَلَهُنَّفَأَمْسِكُوهُنَّبِمَعْرُوفٍأَوْفَارِقُوهُنَّبِمَعْرُوفٍوَأَشْهِدُواذَوَيْعَدْلٍمِنْكُمْ) (At-Talaq: 2) — When these women approach the completion of their waiting period (‘iddah), then either retain them in marriage according to the prescribed manner or separate from them in a good way. And take two just men from among yourselves as witnesses.
It is recommended and superior to appoint witnesses for both divorce (talaq) and taking back (ruju‘).
This is especially the case when the taking back (ruju‘) is verbal.
In the case of taking back (ruju‘) by action, appointing witnesses has no meaning.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 2186