Will the husband be sinful if he has intercourse with his wife who is negligent in prayer and delays it, or must he choose times that enable her to perform ghusl to avoid delaying the prayer?

Performing prayer on time is among the most obligatory duties, and delaying it is a grave sin. The wife must be reminded and warned of God's punishment if she becomes lazy in prayer or performs it without ritual purity, as Allah Almighty says: "O you who have believed, protect yourselves and your families from a Fire." As for engaging in sexual intercourse with the wife, there is no sin in it, and this is indicated by the Prophet's (peace be upon him) approval of Abu Dharr (may Allah be pleased with him) when he became ritually impure (junub) and could not find water. However, delaying intercourse until a time when water can be used without difficulty is more preferable, to help the wife perform prayer in the most complete manner.