Sayyiduna Abu Dharr (may Allah be pleased with him) says: I said to the Messenger of Allah (peace and blessings be upon him): I want to spend the night at your place tonight so that I may perform the night prayer following you. The Messenger of Allah (peace and blessings be upon him) said: You will not be able to keep up with my prayer. Nevertheless, the Messenger of Allah (peace and blessings be upon him) woke up and performed ghusl behind a cloth curtain while I turned my face the other way, then I did the same. After that, the Messenger of Allah (peace and blessings be upon him) began the prayer, (and stood for so long that) I (due to fatigue or sleepiness) was hitting my head against the wall. Then Sayyiduna Bilal (may Allah be pleased with him) called the adhan for prayer. The Messenger of Allah (peace and blessings be upon him) said: Have you already given the adhan? He said: Yes. The Messenger of Allah (peace and blessings be upon him) said: Bilal! When you give the adhan, at that time the light goes straight up towards the sky and that is not the true dawn; the true dawn is when the light spreads (horizontally) along the horizon. Then the Messenger of Allah (peace and blessings be upon him) had food brought and ate suhoor.