Musannaf Ibn Abi Shayba 3:4033

Abdullah ibn Numayr narrated to us, from Hajjaj, from Qarzah, from Mujahid, who said: I saw Ibn Umar pray the two rak'ahs of Fajr, then he sat in the *ihtiba* position (sitting with the knees drawn up to the chest, held by the arms), and he did not speak until he prayed the morning prayer (al-ghadah).