السلام عليكم
"....
With regard to all other words of the prayer, it does not matter if you say them simultaneously with the imam, or before him, or after him. If we assume that you hear the
imam reciting the
tashahhud, and you have already recited it, this does not matter, because
anticipating the imam in the words of prayer, apart from the first takbeer and the salaam, does not affect the prayer.
Similarly it does not matter if you recite al-Faatihah before him and say
Wa laa’l-daalleen “
nor of those who went astray” [al-Faatihaah 1:7 – interpretation of the meaning], whilst he is still reciting
Iyyaaka na’abudu wa iyyaaka nasta’een “
You (Alone) we worship, and You (Alone) we ask for help (for each and everything)” [al-Faatihaah 1:7 – interpretation of the meaning], in
Zuhr prayer, for example, because it is prescribed in
Zuhr and ‘
Asr prayer for the imam to let the people hear the verse he is reciting sometimes, as the Messenger of Allaah (peace and blessings of Allaah be upon him) used to do.
The second category is to do the actions of prayer simultaneously with the imam, and this is
makrooh.
For example, when the imam says “
Allaahu akbar” for
rukoo’, and starts to bend forward, and you start to bow simultaneously with the imam, this is
makrooh, because the Messenger (peace and blessings of Allaah be upon him) said, “
When he bows, then bow, and do not bow until he bows.” And in
sujood when he says
takbeer for
sujood, if you prostrate and reach the floor at the same time as him, this is
makrooh, because the Messenger (peace and blessings of Allaah be upon him) disallowed that and said, “
Do not prostrate until he prostrates.” ..."
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1. https://islamqa.info/en/answers/3379...imam-in-prayer