The Messenger of Allah ﷺ saw a man praying alone and said, "Is there no one who will give charity to this man by praying with him?"
حدثنا موسى بن إسمعيل حدثنا وهيب عن سليمان الأسود عن أبي المتوكل
أن رسول الله ﷺ أبصر رجلا يصلي وحده فقال ألا رجل يتصدق على هذا فيصلي معه
[Its chain of transmission is sahih. Tirmidhi narrated it in the Book of Prayer, Chapter on What Has Been Said Regarding Congregational Prayer in a Masjid Where Prayer Has Already Been Performed Once, hadith no. 220, from the hadith of Sulayman bin Aswad Naji through this chain, and he said, "Hasan," adding, "So a man stood and prayed with him." Ibn Khuzayma graded it sahih (no. 1632), as did Ibn Hibban (hadith nos. 436–438) and Hakim (1/209), and Dhahabi agreed with him.