Is it considered a sin to delay the post-prayer ذكر (dhikr) and the two rak'ahs of the Sunnah prayer until after eating for a fasting person?

As for the prescribed remembrances (adhkar) after the obligatory prayer, the Sunnah is to connect them immediately with the prayer. However, regarding the Sunnah prayer of Maghrib, there is no harm in delaying it. This has been authentically reported from some of the Salaf, including Companions and others. Among what has been reported in this regard is from Maymun ibn Mihran, who said: "Hudhayfah prayed Maghrib in congregation. When the Imam finished the prayer, a man next to him stood up, intending to pray the two rak'ahs. Hudhayfah pulled him back and said: 'Sit down, there is no harm in delaying these two rak'ahs; wait a little.'" And from Maymun, he said: "They used to prefer delaying the two rak'ahs after Maghrib until the stars became visible." And from Ibn 'Awn, he said: "When Raja' ibn Haywah prayed Maghrib, he would not pray anything after it until the twilight disappeared."