"The Prophet (may Allaah raise his rank and grant him peace) did not pray on them consistently, rather he prayed on them only occasionally, and for a reason, like the extreme heat or the likes. [As opposed to those who make it their Religion to pray on them all the time.]"
A question recently came up regarding the use of the prayer rug in salaah. In my quest to find the answer, I came across these helpful resources:
Common Acts of Religious Excessiveness (Ghuluww) Regarding “Prayer Rugs”
Comprehensive 8 point treaty on the use of prayer rugs in salaah from the example of the Prophet (sallAllahu alayhi wa sallam)
Discusses prayer rug sizes and materials, conditions under which it is impermissible to use a prayer rug and more.