Salamu'alaikum. Please is it permissible for someone to spend longer time in Sujud while the Imam had already gotten up? If no, kindly help me with the Hadith that prohibits that. Jazakumullah Khairan.
Allah's Messenger (ﷺ) during his illness prayed in his house sitting, whereas some people followed him standing, but the Prophet (ﷺ) beckoned them to sit down. On completion of the prayer he said, "The Imam is to be followed. So, bow when he bows, and raise your head when he raises his head." (See Hadith No. 657 Vol 1 for taking the verdict).
The Messenger of Allah (ﷺ) said: 'The Imam is appointed to be followed, so when he says the takbir, say the takbir, and when he recites, be silent.'
.... The imam is appointed to be followed as a leader, so do not oppose him.' Abu Hurayra said, 'The one who raises his head and lowers it before the imam - his forelock is in the hand of a shaytan.
You must follow the imam as else you may risk that you prayer would be invalid according the opinion of some scholars. Note that imam in Arabic means leader! The imam of a congregation leads the prayer.
The main reference are the ahadith which have been narrated on the authority of Anas ibn Malik (see in Sahih al-Bukahri 1, 2 3 and Jami' at-Tirmidhi), abu Hurrairah (see in Sunan ibn Majah and Sunan abi Dawod), Hittan ibn 'Abdullah (Sunan an-Nasa-i), 'Aisha (see in Sahih al-Bukhari and Sahih Muslim) and many more similar ahadith and narrations.
Imam an-Nawawi commented the hadith as follows:
This is my own translation take it with the necessary care
وفيه وجوب متابعة المأموم لإمامه في التكبير والقيام والقعود والركوع والسجود وأنه يفعلها بعد الإمام
This hadith shows that the ma'umum is asked (wajib) to follow his imam, in his takbeer, standing, sitting, bowing and prostrating and that he has to do what the imam has done after the imam. (Source fatwa on islamweb #121568
Note that salat in congregation is a symbol of unity if you prolonged your sujud you would be like a misfit in the jama'a also it may lead you to riya' as you may come to the conclusion that you are more pious than the rest ...
There are ahadith on the opposite situation if a person for example stands up before the imam too.
In this fatwa on islamqa #33790 all the four cases that may happen to a ma'mum in a congregation prayer (Anticipation (doing a movement before the imam), Delay, Doing an action simultaneously with the imam and Following) are discussed.