It is narrated from Uthman bin Abdullah bin Saraqah that he saw Hafs bin Asim performing voluntary (nafl) prayers during a journey, and in that journey, Abdullah bin Umar (may Allah be pleased with them both) was also with him. So it was said to him that your maternal uncle (Abdullah bin Umar, may Allah be pleased with them both) forbids this. So I asked Ibn Umar (may Allah be pleased with them both) about this, and he said: I saw the Messenger of Allah (peace and blessings be upon him) that he did not do this. The Messenger of Allah (peace and blessings be upon him) would not perform (nafl) prayers before or after the obligatory prayers. I asked: Can I perform (nafl) prayers at night? He replied: Perform as many (nafl) prayers at night as you wish.