Prayer on a Ship

 he (sallallaahu 'alaihi wa sallam) was asked about prayer on a ship, so he said, pray on it standing, unless you are afraid of drowning.²¹

when he grew old he took a support at his place of prayer to lean on²².  

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 21 bazzaar (68), daaraqutni, `abdul ghani al-maqdisi in his sunan (82/2) and haakim declared it saheeh and dhahabi agreed.

22 abu daawood and haakim, who declared it saheeh, as did dhahabi. i have given it in as-saheehah (319) and irwaa' (383)