Haafiz Ibnu Sayyidin Naas (rahimahullah) has mentioned in Uyoon-ul-Athar that when Rasulullah (sallallahu ‘alaihi wasallam) established the pact of brotherhood between the Muhaajireen Sahaabah (radhiyallahu ‘anhum) in Makkah Mukarramah, before the hijrah, then he paired the following people with each other:

1. Hazrat Abu Bakr (radhiyallahu ‘anhu) and Hazrat Umar (radhiyallahu ‘anhu)

2. Hazrat Hamzah (radhiyallahu ‘anhu) Hazrat Zaid bin Haarithah (radhiyallahu ‘anhu)

3. Hazrat Uthmaan Ghani (radhiyallahu ‘anhu) and Hazrat Abdur Rahmaan bin Awf (radhiyallahu ‘anhu)

4. Hazrat Zubair bin Awwaam (radhiyallahu ‘anhu) and Hazrat Abdullah bin Mas’ood (radhiyallahu ‘anhu)

5. Hazrat Ubaidah bin Haarith (radhiyallahu ‘anhu) and Hazrat Bilaal bin Rabaah (radhiyallahu ‘anhu)

6. Hazrat Mus’ab bin Umair (radhiyallahu ‘anhu) and Hazrat Sa’d bin Abi Waqqaas (radhiyallahu ‘anhu)

7. Hazrat Abu Ubaidah (radhiyallahu ‘anhu) and Hazrat Saalim, the freed-slave of Hazrat Huzaifah (radhiyallahu ‘anhu)

8. Hazrat Sa’eed bin Zaid (radhiyallahu ‘anhu) and Hazrat Talhah bin Ubaidillah (radhiyallahu ‘anhu)

9.Hazrat Sayyiduna Rasulullah (sallallahu ‘alaihi wasallam) and Hazrat Ali (radhiyallahu ‘anhu)

(Seeratul Mustafa 1/436-437)