Sahih Ibn Khuzaymah

In the narration of Sayyiduna Abu Hurairah (may Allah be pleased with him), it is mentioned that the Noble Prophet (peace and blessings of Allah be upon him) was informed that Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) was leading in prayer those people who did not have the Qur'an memorized. So the Prophet (peace and blessings of Allah be upon him) approved of his action and said, "He has done the right or a very good thing."

In the narration of Sayyiduna Abu Dharr (may Allah be pleased with him), the Messenger of Allah (peace and blessings be upon him) said: "When a person prays with the Imam until he finishes the prayer, it is written for him as if he stood in prayer for the entire night." And in another narration, it is mentioned that then the Prophet (peace and blessings be upon him) led us in prayer on the third night, and gathered his family and noble wives as well. Then he (peace and blessings be upon him) led such a long prayer that we feared missing out on success. And the companions who prayed with him were reciters and memorizers of the Qur'an. Not all of them were unlettered.

In the statement of the Messenger of Allah (peace be upon him) that "Whoever stands (in prayer) with the Imam until the Imam finishes the prayer, it is written for him as if he spent the whole night in prayer," there is evidence that whether a person is a reciter (of the Qur'an) or unlettered, when he stands with the Imam until the Imam finishes his prayer, it is written for him as if he spent the whole night in prayer. And the reward of standing the whole night is better and superior than the reward of standing for part of the night. This is when, along with standing (in prayer), he also fasted during the days of Ramadan, performed the five prayers regularly, gave zakat, testified to the oneness of Allah, and acknowledged the messengership of the Messenger of Allah (peace be upon him).