What is the ruling on praying behind an imam who moves a number of times during the prayer, but I do not know whether these movements reach the point where they are too much and invalidate the prayer or not?
Firstly:
We are instructed to be calm during the prayer.
It was narrated that Jabir ibn Samurah (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) came out to us and said: “Why do I see you raising your hands like the tails of restive horses? Be calm when praying.” Narrated by Muslim (430).
Any movement that is not part of the prayer and is unnecessary is described as something that goes against this command to be calm, and is something that is contrary to the humble focus that is enjoined in the prayer.
But if the movements are small and are not consecutive, they do not spoil the prayer.
Shaykh `Abd al-`Aziz ibn Baz (may Allah have mercy on him) said:
If it – any movement – is small according to custom, or there are many movements but they are not consecutive, then the prayer is not rendered invalid thereby, but it is prescribed for the believer to maintain his humble focus and avoid any fidgeting, whether the movements are small or great, so as to ensure that he does his prayer properly and perfectly.
The evidence that small actions or movements in the prayer do not invalidate it, and neither do intermittent movements that are not consecutive, is found in the soundly narrated report from the Prophet (blessings and peace of Allah be upon him), which says that one day he opened the door to `A’ishah’s apartment whilst he was praying. It is also soundly narrated from him (blessings and peace of Allah be upon him), in the hadith of Abu Qatadah (may Allah be pleased with him), that he led the people in prayer one day when he was carrying Umamah, the daughter of his daughter Zaynab; when he prostrated, he put her down, and when he stood up he picked her up again.(Majmu` Fatawa wa Maqalat ash-Shaykh `Abd al-`Aziz ibn Baz, 11/113).
But if the movements in prayer are many, consecutive and unnecessary according to Islamic rulings, then they spoil the prayer. Ibn Hazm (may Allah have mercy on him) narrated that there was consensus regarding that, when he said:
The scholars are agreed that eating, laughing out loud and doing any lengthy action that is not enjoined as part of the prayer all invalidate the prayer, if the person does that deliberately and aware that he is in prayer.(Maratib al-Ijma`, p. 51).
There is no religious text which defines the guideline on what is regarded as too much, so it is to be referred to what people regard as being too much. Whatever they think is too much and is contrary to the way in which the prayer is to be done, in the sense that people think that the one who does that is not praying, is something that invalidates the prayer, otherwise it is not.
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said:
The best guideline on this issue is that if we see this person moving, and we think it most likely that he is not praying because he is moving too much, then this is what determines what is too much movement: it is when the movement is such that the one who sees it will think that the person is not praying, because this is contrary to the way in which the prayer should be done.(Ash-Sharh al-Mumti`, 3/256).
Conclusion: if the imam’s movements are many, but not consecutive – rather they are intermittent – then they do not invalidate the prayer. This is what appears to be the case with your imam, as may be understood from your question, because you said that he moves a number of times during the prayer.
But if his movements are many and consecutive, meaning that you think that it is as if he is not praying, then in this case the prayer is invalid, and in this situation the worshipper must look for another imam to pray behind.
And Allah knows best.
