something additional to al-Fātiḥah in ʿAṣr or Dhuhr on occasion, there is no harm in it. Nevertheless, the original Sunnah is to confine the recitation to al-Fātiḥah in the two units that follow the first tashahhud when the prayer is four-rakʿah, or in the third rakʿah when the prayer is three-rakʿah.
Among the pillars of the prayer is bowing (rukūʿ). It is the act of bending down in reverence before Allah, for you are conscious that you are standing in His presence, so you incline yourself in veneration of Him. Concerning this the Prophet (peace and blessings be upon him) said: “As for bowing, magnify the Lord therein,” meaning: say, “Subḥāna Rabbī al-ʿAẓīm” (Glory be to my Lord, the Most Great). Bowing itself is veneration in deed, while saying “Subḥāna Rabbī al-ʿAẓīm” is veneration in word; the two forms of glorification combine with the essential glorification of the heart, for you do not bend in this way except out of reverence for Allah. Thus, in rukūʿ three kinds of glorification converge:
- Veneration of the heart.
- Veneration of the limbs.
- Veneration of the tongue.
With the heart you sense that you have bowed to Allah; with the tongue you say, “Subḥāna Rabbī al-ʿAẓīm”; and with the limbs you lower your back. The obligatory measure in bowing is to bend until you are able to place your hands on your knees. A slight nod is not enough—you must press your back downward until you can do so.