Used one of the chairs in the mosque for Friday Prayers. My back is okay but my right knee was giving me trouble all morning, at times forcing me to walk with a limp, before abruptly righting itself. I decided to take no chances. A sudden inability to bend one's leg properly in the middle of prayers would be highly embarrassing.
It's strange, by the way, how often when you explain to non-Muslims the various compromises we're allowed to make in matters of prayer, or pretty much any aspect of life, they express surprise. Assumptions about the rigidity of the faith abound yet are fundamentally mistaken.
Isn't it strange how often people assume that the more extreme a particular manifestation of faith is, the more authentic it must be?