What does one do if he has started a voluntary prayer and the people have stood for the funeral prayer?

Question:
What is the ruling if the funeral prayer is present and I am praying the regular voluntary prayer?

Answer:
If the funeral prayer is present and you are in the middle of the regular voluntary prayer, complete the regular voluntary prayer. Complete the regular voluntary prayer; it is not permissible for you to cut it off.
So, once you have completed the regular voluntary prayer, if you catch any part of the funeral prayer, join them in the remainder, in the remainder of the funeral prayer, and consider it the beginning of the funeral prayer for you. Then, when the imam concludes the prayer, complete the funeral prayer in its proper form. For example, if you say the first takbir with the imam, and the imam concludes the prayer after you have said the first takbir, you recite al-Fatihah.
Even if it is the imam's last takbir, or if it is the imam's third takbir, consider it your first takbir and recite al-Fatihah after it. Then, when the imam concludes the prayer, you say the second takbir, you say the second takbir and send blessings upon the Prophet (peace and blessings be upon him), then you say the third takbir and make du'a for the deceased, then you say the fourth takbir and conclude the prayer. And if you fear that the funeral will be lifted before you complete your prayer over it, then you say the takbirs in succession, saying them one after another, and conclude the prayer. This is sufficient, and praise be to Allah.