بسم الله الرحمن الرحيم
Al-Imam al-Bukhari made chapter in his Saheeh:
باب: يقوم عن يمين الإمام بحذائه سواء ، إذا كانا اثنين
Chapter: He stands on the right of the Imam next to him equally if those (praying) are two.
Al-Haafidh Ibnu Hajr mentioned rahimahullaah in Fath al-Baree (2/160):
The statement of (al-Bukhari in title of the chapter) “equally” it means he does not preceed (the imam) nor does he remain behind him.
And it is as if the author (al-Bukhari) is pointing towards what has come in some of the chains of narration in the hadeeth of Ibn Abbas; for indeed the wording (which is found in the hadeeth where Ibn Abbaas) said:
فقمت إلى جنبه
So I stood beside him (sallallahu alaihi wa sallam)
(And) what is apparently (intended) is (that they were) even or equal in position.
Note: the hadeeth which al-Haafidh is referring to has been reported by al-Bukhari (937) and Muslim (1283) on the authority of Ibn Abbas radhiallaahu Anhu.
Al-Imam al-Albani rahimahullaah also stated in as-Saheeha hadeeth number (2590):
The Sunnah is that the one praying follows the Imam whilst he is on the right side (of the Imam) and while he is equal to him, not in front of him nor behind him. In opposition to what is (found) in some schools of jurisprudence that it is befitting to remain behind the Imam just slightly by placing the toes of the feet equal to the heals of the Imam or similar to this.
We ask Allaah to benefit us by way of this small effort and all praise is due to Him Lord of all that exists.
Written by Noble brother Abu ‘Atiyah Mahmood as-Somali