It is narrated from Sayyiduna Yusuf bin Abdullah bin Salam (may Allah be pleased with him), he says: I went to serve Sayyiduna Abu Darda (may Allah be pleased with him) for the sake of acquiring knowledge, when the time of his death approached. He said to me: Inform the people of my death. I informed the people of his death, and when I returned, his house and the surrounding places were filled with people. I went and said to him: I have informed the people of your death and the house and the surrounding places have filled with people. He said to me: Take me outside. We took him outside. He said: Make me sit down. We made him sit down. He said: O people! I heard the Messenger of Allah (peace and blessings be upon him) say that whoever performs ablution properly and then performs two units of prayer completely, then whatever he asks Allah for in supplication, Allah will surely grant him his desired thing, sooner or later. Then he said: O people! Do not look here and there in prayer. Whoever looks here and there, his prayer is not valid. If there is a need for it in voluntary prayer, then it is permissible, but do not allow it in obligatory prayer.