When Abdullah bin Umar came to the masjid and found that the people had already prayed, he would begin with the obligatory prayer and would not pray anything before it.
و حدثني عن مالك
أن عبد الله بن عمر كان إذا جاء المسجد وقد صلى الناس بدأ بصلاة المكتوبة ولم يصل قبلها شيئا