During the journey of Tabook, the Sahaabah (radhiyallahu ‘anhum) were traveling with Rasulullah (sallallahu ‘alaihi wasallam). Rasulullah (sallallahu ‘alaihi wasallam) left the Sahaabah (radhiyallahu ‘anhum) to go and relieve himself.
Since there was not a lot of time remaining for the fajr salaah, and the Sahaabah (radhiyallahu ‘anhum) feared that the time would expire, they did not wait for Rasulullah (sallallahu ‘alaihi wasallam) to return, but requested Hazrat Abdur-Rahman ibn Auf (radhiyallahu ‘anhu) to lead them in the fajr salaah.
Hazrat Abdur-Rahman ibn Awf (radhiyallahu ‘anhu) accepted and commenced the salaah. While he was leading the salaah, Rasulullah (sallallahu ‘alaihi wasallam) returned and joined the salaah. Rasulullah (sallallahu ‘alaihi wasallam) stood in the saff behind Hazrat Abdur-Rahman ibn Awf (radhiyallahu ‘anhu).
Some of the Sahaabah (radhiyallahu ‘anhum) began reciting tasbeeh in order to inform Hazrat Abdur-Rahman ibn Awf (radhiyallahu ‘anhu) that Rasulullah (sallallahu ‘alaihi wasallam) has returned so that he may move back, and Rasulullah (sallallahu ‘alaihi wasallam) may move forward and lead the salaah.
When Hazrat Abdur-Rahman ibn Awf (radhiyallahu ‘anhu) realized that Rasulullah (sallallahu ‘alaihi wasallam) was standing behind, he intended to move back, however Rasulullah (sallallahu ‘alaihi wasallam) indicated to him with his hand to remain where he was and continue leading the salaah.
After completing the salaah, Rasulullah (sallallahu ‘alaihi wasallam) addressed the Sahaabah (radjiyallahu ‘anhum) saying, ‘You have done well,” or he said to them, “You have acted correctly (by commencing the salaah and not waiting for me.” In other words, the Sahaabah (radhiyallahu ‘anhum) were concerned at that time that Rasulullah (sallallahu ‘alaihi wasallam) should not be displeased with them due to them not waiting for him, however Rasulullah (sallallahu ‘alaihi wasallam) consoled and comforted them that in such a situation, they had done the correct thing.
(Sunan Abi Dawood #149, Sharhuz Zurqaani Alal Mawaahibil Ladunyah 2/208, Bazlul Majhood 1/638-643)