1031. In every Rak'at, a person offering prayers should, after reciting the Surahs (Qira'at), bow to an extent that he is able to rest his finger tips on his knees. This act is called Ruku.
1032. If the person performs Ruku in an unusual manner, like, if he bends towards left or right, his Ruku is not correct even if his hands reach his knees.
1034. Bending should be with the niyyat of Ruku. If a person bends for some other purpose (e.g. to kill an insect), he cannot reckon it as Ruku. He will have to stand up and bend again for Ruku, and in so doing, he will not have added any Rukn, nor will his prayers be void.
1035. If a person has abnormally long hands, so that if he bends a little they reach his knees, or if his knees are lower than usual, so that he has to bend himself lower to make his hands reach his knees, he should follow the normal bowing by the others.
1036. A person who performs Ruku in the sitting position, should bow down till his face is parallel to his knees. And it is better that he should bow down till his face reaches near the place of Sajdah.
1037. It is better that in normal situations one should say in Ruku, Subhanallah three times or Subhana Rabbiyal 'Azimi wa bi hamdih once. But actually, uttering any Zikr to this extent is sufficient. However, if namaz time is short, or if one is under any pressure, it will be sufficient to say Subhanallah once.
1038. The Zikr of Ruku should be uttered in succession, and in correct Arabic, and it is Mustahab that it should be uttered 3, 5 or 7 times or more than that.
1039. In Ruku, the body should be steady, and one should not purposely move or shake oneself. And as a precaution, one should not have any movement when reciting the obligatory Zikr.
1040. If at the time of uttering the obligatory Zikr of Ruku, he loses steadiness because of uncontrollable vigorous movement, it will be better that after his body resumes steadiness he repeats the Zikr. However, if the movement is so negligible that steadiness is not lost, or if he just moves his fingers, there is no harm in it.
1041. If a person intentionally recites the Zikr of Ruku before he has properly bowed down, and before his body becomes still, his prayers will be void.
1042. If a person intentionally raises his head from Ruku before completing obligatory Zikr, his prayer is void. If he raises his head by mistake, and if he has not completely ceased to be in Ruku and he recollects that he has not completed the Zikr of Ruku, he should make himself steady and recite the Zikr. And if he recollects after he has arisen totally from Ruku, his prayers are in order.
1043. If a person is unable to remain in the state of Ruku all the time while reciting the Zikr, then the recommended precaution is that he should complete the remainder while standing up from Ruku.
1044. If a person cannot remain steady during Ruku owing to some disease etc, his prayers are in order. But he should complete the obligatory part of Zikr, as explained, before totally rising from Ruku.
1045. If a person cannot bow down for Ruku properly, he should lean on something and perform Ruku. And if he cannot perform Ruku even after he has leaned, he should bow down to the maximum extent he can, so that it could be customarily recognized as a Ruku. And if he cannot bend at all, he should make a sign for Ruku with his head.
1046. If a person supposed to make a sign with his head for Ruku is unable to do so, he should close his eyes with the niyyat of Ruku, and then recite Zikr. And for rising from Ruku, he should open his eyes. And if he is unable to do even that, he should, as a precaution, make a niyyat of Ruku in his mind, and then make a sign of Ruku with his hands and recite Zikr.
1047. If a person cannot perform Ruku while standing, but can bend for it while sitting, he should offer prayers standing and should make a sign with his head for Ruku. And the recommended precaution is that he should offer another prayers in which he would sit down at the time of Ruku, and bow down for it.
1048. If some one raises his head after reaching Ruku, and bows down twice to the extent of Ruku, his prayer is void.
1049. After the completion of the Zikr of Ruku, one should stand straight, and proceed to Sajdah after the body has become steady. If one goes to Sajdah intentionally before standing erect, or before the body is steady, the prayers are void.
1050. If a person forgets to perform Ruku, remembering it before Sajdah, he should stand up first, and then go into Ruku. It will not be proper for him to go into Ruku in a bent position.
1051. If a person offering prayers remembers after his forehead reaches the earth, that he has not performed Ruku, it is necessary that he should return to standing position and then perform Ruku. But, if he remembers this in the second Sajdah, his prayers are void.
1052. It is Mustahab that before going into Ruku, a person should say Takbir while he is standing erect, and in Ruku, he should push his knees back, keep his back flat, stretch forth his neck, keep it in line with his back, look between his two feet, say Salawat before or after Zikr. And when he rises after Ruku, it is Mustahab to stand erect, and in a state of steadiness say Sami'allahu liman hamidah.
1053. It is Mustahab for women that while performing Ruku, they should keep their hands higher than their knees, and should not push back their knees.