وَالسُّجُودُ عَلَى مَا يَجِدُ حَجْمَهُ وَتَسْتَقِرُّ عَلَيْهِ جَبْهَتُهُ
The forehead must settle on a surface with enough resistance that it does not keep sinking under pressure. A very soft cushion in which the forehead never settles does not fulfill this condition.
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Prayer Pillars: Ruku and Sujud
وَالسُّجُودُ عَلَى مَا يَجِدُ حَجْمَهُ وَتَسْتَقِرُّ عَلَيْهِ جَبْهَتُهُ
The forehead must settle on a surface with enough resistance that it does not keep sinking under pressure. A very soft cushion in which the forehead never settles does not fulfill this condition.