If a person cannot remain in the position of rukūʿ for the length of the dhikr – not even for saying one subḥānal lāh, even without being still – then it is not obligatory for him to say it. However, the recommended precaution is that he say the dhikr even if he says the rest of it while rising from rukūʿ with a general intention of attaining proximity to Allah (qaṣd al‑qurbah al‑muṭlaqah) [i.e.

with the intention of attaining proximity to Allah without specifying it is an obligatory dhikr of the prayer]. Alternatively, he should start before that [i.e. he should start saying the dhikr before reaching the position of rukūʿ with a general intention of attaining proximity to Allah].