Assalaamu alaykum wa rahmatullaahi wa barakaatuhu, Shaykh. Is it permissible to pray on a "high" chair/sitting tool with one's feet not touching the ground? (For someone who suffers if their feet are placed on the ground.) May Allaah reward you, Shaykh.

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.

There is no harm for someone who finds it difficult to stand to pray sitting down because the Prophet said to ‘Imraan ibn Husayn: “Pray while standing, and if you are not able to stand, then pray while sitting.” [Al-Bukhaari]

The one who is not able to stand may pray on a chair or on anything else, regardless of whether his feet touch the ground or not. If he cannot prostrate on the ground, then he nods for the bowing and the prostration; and he makes his nodding for the prostration lower than that for the bowing.

Allah knows best.