The ruling on cutting off a voluntary prayer when the call to prayer is made
Machine translationRead the Arabic original
Question:
What should one do if the call to prayer for the obligatory prayer is made while the worshiper has already begun a voluntary prayer?
Answer:
If he is in the last part of it, he completes it. But if he is in the first part, he breaks it off. The Messenger of Allah (peace and blessings be upon him) said: "When the call to prayer is made, there is no prayer except the one that is connected to it." If he is in the last part, he completes it. But if he is in the first part, he breaks it off and prays the obligatory prayer with the imam. Yes.
What should one do if the call to prayer for the obligatory prayer is made while the worshiper has already begun a voluntary prayer?
Answer:
If he is in the last part of it, he completes it. But if he is in the first part, he breaks it off. The Messenger of Allah (peace and blessings be upon him) said: "When the call to prayer is made, there is no prayer except the one that is connected to it." If he is in the last part, he completes it. But if he is in the first part, he breaks it off and prays the obligatory prayer with the imam. Yes.
Source
نور على الدرب - الفوزان - 03/058 — archive.org (7:56)
The Arabic text is a machine transcription of the audio recording.