The Messenger of Allah ﷺ was never asked for anything in exchange for accepting Islam without giving it. A man came to him and asked, so he ordered that a great flock of sheep be given to him, filling the space between two mountains, all from the sheep of charity. The man returned to his people and said, "My people, accept Islam, for Muhammad ﷺ gives so generously that he has no fear of poverty."
حدثنا ابن أبي عدي عن حميد عن موسى بن أنس
أن رسول الله ﷺ لم يكن يسأل شيئا على الإسلام إلا أعطاه قال فأتاه رجل فسأله فأمر له بشاء كثير بين جبلين من شاء الصدقة قال فرجع إلى قومه فقال يا قوم أسلموا فإن محمدا ﷺ يعطي عطاء ما يخشى الفاقة