The general custom throughout the ages is that friends and family share in the joyous and sad occasions of one another. Following this, Sayyidina ‘Umar invited Sayyidina ‘Ali radiya Llahu ‘anhuma with others for his nikah and walimah and the latter accepted the invitation wholeheartedly and attended. An incident also occurred in which Sayyidina ‘Ali radiya Llahu ‘anhu had an informal moment. Although the incident appears in many books, we will suffice on the report of al Isti’ab for purposes of brevity since it is a well-known and easy accessible book. The references of other books will be provided.
فتزوجها (عاتكة بنت زيد بن عمرو بن نفيل) عمر بن الخطاب سنة اثنتي عشر فأولم عليها فدعا جمعا فيهم علي بن أبي طالب فقال يا أمير المؤمنين دعني أكلم عاتكة قال افعل فأخذ بجانبي الباب و قال يا عدية نفسها أين قولك فآليت لا تنفك عيني حزينة عليك و لا ينفك جلدي أغبرا فبكت فقال عمر ما دعاك إلى هذا يا أبا الحسن كل نساء يفعلن هذا إلخ
‘Umar ibn al Khattab married ‘Atikah bint Zaid ibn ‘Amr ibn Nufayl in the year 12 A.H. He prepared a walimah feast after consummating the marriage and invited many people including ‘Ali ibn Abi Talib. During the ceremony, ‘Ali said, “Amir al Mu’minin, allow me to have a word with ‘Atikah.”
“Go ahead,” he consented.
‘Ali held the sides of the door and said, “O enemy of yourself, what happened to your couplet (which she read at the death of her previous husband ‘Abdullah ibn Abi Bakr): ‘I have sworn that my eyes shall remain grief stricken over you and my skin shall wear dust’?”
Hearing this, she began to cry. ‘Umar said, “What made you do this, Abu al Hassan? All women are such (they forget the past and get involved in new things).”
From the narrations of this section it becomes manifest that Sayyidina ‘Umar radiya Llahu ‘anhu held the children of Rasulullah salla Llahu ‘alayhi wa sallam in high esteem. He also considered their status and respected them. He maintained an amiable relationship with them and continued fulfilling the rights of companionship. He also sustained his friendly relationship with Sayyidina ‘Ali radiya Llahu ‘anhu. They shared in each other’s times of happiness and sadness. They invited each other and accepted such invitations. There existed no ill-feelings for each other. All these stories are testimonials to this.
 Al Isti’ab, vol. 4 pg. 355, with al Isabah, discussion on ‘Atikah; Nasab Quraysh, vol. 1 pg. 365, discussion on the children of ‘Adi ibn Ka’b; Ibn ‘Abdul Barr: Kitab al Tamhid, vol. 6 pg. 252, the narrations of Yahya ibn Sa’id Hadith: 46, Qilmi Pir Jhanda, Sindh; Usd al Ghabah, vol. 5 pg. 498, mention of ‘Atikah bint Zaid.