Sayyiduna ‘Ali (radiyallahu ‘anhu) says,
“I was once with Rasulullah (sallallahu ‘alayhi wa sallam), Abu Bakr and other Sahabah were with as well. We passed by ‘Abdullah ibn Mas’ud who was performing Salah. Upon inquiring, Nabi (sallallahu ‘alayhi wa sallam) was informed that the person performing Salah was ‘Abdullah ibn Mas’ud. Nabi (sallallahu ‘alayhi wa sallam) then said, ‘Abdullah [ibn Mas’ud] recited Quran just as it was revealed.
Sayyiduna ‘Abdullah ibn Mas’ud [unaware that he was being watched] then praised Allah in the best manner and made a beautiful du’a unto Allah. Then he said,
‘Allahumma inni as-aluka imanan la yartad wa na’iman la yanfad wa murafaqata Muhammadin (sallallahu ‘alayhi wa sallam) fi a’ala ‘illiyyin fi Jannatika jinanal khuld’
When Rasulullah (sallallahu ‘alayhi wa sallam) heard him praising Allah and heard him make this du’a, he said twice, ‘ask and you shall be granted’.
Sayyiduna ‘Ali (radiyallahu ‘anhu) then went to convey the glad tidings, but learnt that Sayyiduna Abu Bakr had already conveyed the glad tidings to ‘Sayyiduna ‘Abdullah ibn Mas’ud. Sayyiduna ‘Ali says, [Abu Bakr] was a forerunner of all good”
(Mustadrak Hakim, vol. 3 pg. 317)