if he stands up for a voluntary prayer he does not have the right to let them pray voluntary prayers because they do not know that he might precede them or interrupt his prayer due to an accident and he would need to precede them and he is standing and they pray opposite him while he is sitting. but he has the right that they be in their state so that they know what he is doing. if he sits they should turn to a place where he cannot see them and pray their voluntary prayers. if he starts praying they pray in their places.
فإن قام لنافلة، فليس من حقه أن يتنفلوا، لأنهم لا يدرون لعله أن يسبقهم أو يقطع صلاته لحدث، فيكون يحتاج إلى أن يسبقهم، وهو قيام يصلون بإزائه، وهو قاعد. ولكن من حقه أن يكونوا بحالهم حتى يعلموا ما الذي يفعل. فإن قعد، انحرفوا إلى حيث لا يراهم، فصلوا نوافلهم، وإن دخل في الصلاة، صلوا على مكاناتهم.