question #2 Sahih Muslim 467a, Book 4, Hadith 208 : How does the presence of diverse individuals in a congregation affect the length of the prayer?

The Apostle of Allah (ﷺ) said: When any one of you leads the people in prayer, he should be brief for among them are the young and the aged, the weak and the sick. But when one of you prays by himself, he may (prolong) as he likes.