If you are referring to the sitting position between the two prostration, if you don’t say rabbighfirli and you don’t say the prescribed thikr intentionally, your prayer is invalid.

Sheikh if i dont say rabbigh fir lee in Salaah intentionally.is my prayer valid

Prayer | October 16, 2017 6:48 am
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During the juma lecture can we pray Tahayyatul Masjid? some says you can”t even fidget with anything then how you will pray. Please can you quote from Hadith.
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If a man does not pray , fast regularly in ramadhan , and always try to earn money and does not follow the Quran and Sunnah , does this means he is worshiping something or someone other than Allah , such as money,etc.