What is the ruling on performing prayer on thick prayer mats or carpets?

Shaykh Ṣāliḥ al-Fawzān – may Allah preserve him – was asked: Is it permissible to perform prayer on an elevated surface such as a bed or the like if a person doubts the purity of the ground, without having an excuse such as illness or the like? He replied: “There is no harm in a person praying on something elevated like a bed or similar, as long as it is pure and stable—meaning it does not cause shaking or imbalance for the one praying, nor distraction.” End of quote from Al-Muntaqā (2/143).