Evidence that the one who is able to stand but not to bow should indicate the bowing
Machine translationRead the Arabic original
Question : He is able to stand, but he cannot bow.
Answer : We tell him: Pray standing and indicate the bowing while standing. The evidence is: "Fear Allah as much as you are able." All right.
Answer : We tell him: Pray standing and indicate the bowing while standing. The evidence is: "Fear Allah as much as you are able." All right.
Source
قناة «فضيلة الشيخ محمد بن صالح العثيمين»، 3715دليل أن من قدر على القيام ولا يقدر على الركوع يومئ..📔 الشرح الممتع على زاد المستقنع - ابن عثيمين — youtube.com
The Arabic text is a machine transcription of the audio recording.