The Holy Prophet (Sallallahu alaihi wa sallam) would stand for such long periods of time in His Salaat that His feet would swell up as is established through this Hadith of Sahih Bukhari:
Translation: Hadhrat Zyad has related that he heard Hadhrat Mugheera (May Allah be well pleased with him) say that the Holy Prophet (Sallallahu alaihi wa sallam) stood for so long in Salaat that His feet got swollen. (Sahih Bukhari, Hadith No. 4836)
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