What is the difference between the obligatory prayer and the voluntary prayer?

Question:
The questioner: (Ibrahim . A) from Riyadh has a set of questions. He asks: Is there a difference between the obligatory prayer and the voluntary prayer?

Answer:
Yes, there is a difference. The voluntary prayer is recommended, and the obligatory prayer is obligatory. If one leaves the voluntary prayer, he does not commit a sin. If he leaves the Duha prayer, or the Witr prayer, or the regular voluntary prayers attached to the midday, dawn, sunset, or night prayers, he does not commit a sin. But if he leaves the obligatory prayer, he commits a sin. In fact, he becomes a disbeliever if he leaves the obligatory prayer and intentionally neglects it.
In the voluntary prayer, it is permissible for him to pray while sitting, even if he is healthy. In the obligatory prayer, he is not allowed to pray while sitting except in the case of an excuse, such as illness or inability. As for the voluntary prayer, if he prays while sitting, there is nothing wrong with it. The Prophet (peace and blessings be upon him) used to pray while sitting in the night prayer, and he said: (peace and blessings be upon him). So if he prays while sitting in the night or in the day for the voluntary prayer, there is no blame on him. But in the obligatory prayer, that is not the case; he must pray standing. This is based on his saying (peace and blessings be upon him) in the hadith of Imran: He said to Imran ibn al-Husayn (may Allah be pleased with him) : This applies to the obligatory prayer. As for the voluntary prayer, there is no blame; he may pray while sitting if he is lazy and sits down, and there is no blame. Yes.