Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: "When the imam says the salam and a man has some need, he should not wait for the imam to turn his face towards him, for the conclusion of the prayer is the salam." So when Sayyiduna Abdullah (may Allah be pleased with him) said the salam, he would not delay but would stand up or move from his place, and turn his face towards the people.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9307