Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.139.

Section : Sunnah acts of prayer, Recitation after al-Fatihah.

Here we shall mention what Ibn al-Qayyim learned about the Prophet’s recitation following al-Fatihah in different prayers. He commented, “When the Prophet finished al-Fatihah, he would sometimes make a lengthy recitation, and sometimes a short one if he was travelling or similarly engaged. But most of the time, he made a recitation of intermediate length.