It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that if a person declares his wife forbidden upon himself, then this is an oath for which he should give expiation (his wife will not be divorced), and he used to present this verse as evidence: «﴿لَقَدْكَانَلَكُمْفِيرَسُولِاللَّهِأُسْوَةٌحَسَنَةٌ﴾ [الأحزاب : 21]» "Indeed, in the Messenger of Allah you have an excellent example."
Hadith Referenceمسند احمد / ومن مسند بني هاشم / 1976
Hadith Gradingحکم دارالسلام:حديث عكرمة عن عمر فيه انقطاع ، لان عكرمة لم يدرك عمر ، وحديث يعلي بن حكيم صحيح، خ: 5266، م: 1473.