Is there a reward for delaying breaking the fast until after Maghrib prayer?

Delaying iftar (breaking the fast) carries no reward. Rather, it is better to hasten breaking the fast immediately after sunset, because the Prophet, peace and blessings be upon him, said: "People will remain upon goodness as long as they hasten the breaking of the fast." This is also because the Jews and Christians delay it, and in hastening it, there is opposition to them. Aisha, may Allah be pleased with her, was asked about hastening the Maghrib prayer and iftar, and she said: "This is how the Messenger of Allah, peace and blessings be upon him, used to do it."

Among the wisdoms behind hastening iftar are: opposing the Jews and Christians, following the Sunnah, not extending the day into the night, that it is gentler on the fasting person and strengthens them for worship, and taking the initiative to consume what Allah has made lawful. Scholars have agreed that this applies when the sunset has been verified.