Bayhaqi 2880 — Supplication in prayer

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Prophet (peace and blessings be upon him), Abu Bakr and Umar (may Allah be pleased with them both), the three of them, went out. Abu Bakr (may Allah be pleased with him) had invited him (peace and blessings be upon him). They went out from his (Abu Bakr's) house towards the mosque of Madinah, the Prophet's Mosque. Abdullah (may Allah be pleased with him) was standing in prayer, reciting. Then he sat and recited the tashahhud, then he praised and glorified Allah abundantly, then he sent blessings upon the Prophet (peace and blessings be upon him), then he supplicated with great humility, while the Prophet (peace and blessings be upon him) stood listening attentively. He (peace and blessings be upon him) began to say: "Ask, and whatever you ask for will be given to you." Abu Bakr (may Allah be pleased with him) said: O Messenger of Allah, who is this? He (peace and blessings be upon him) said: "This is Abdullah, the son of Umm Abd (may Allah be pleased with him). Whoever would like to recite the Qur'an fresh, just as it was revealed, let him recite it the way Ibn Umm Abd (may Allah be pleased with him) was reciting."
Abu Bakr al-Siddiq and Umar (may Allah be pleased with them both) hurried to him, and Abu Bakr got ahead of Umar (may Allah be pleased with them both). Umar (may Allah be pleased with him) was certain that Abu Bakr (may Allah be pleased with him) had got ahead of him, so Umar (may Allah be pleased with him) said: He is always the first to every good deed.