Sunan Abi Dawud 794
سنن أبي داود#794SahihAbu Hurairah reported the prophet (ﷺ) as saying:When one of you leads the people in prayer, he should be brief, for among them are the weak, the sick, and the aged. But when one of you prays by himself, he may pray as long as he likes
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Bukhari (703)
In-book reference: 2:404