It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Muhajirun said: "O Messenger of Allah (peace and blessings be upon him), we have never seen a people like those we have come to in Madinah, more generous in giving when they have much, nor better in sharing when they have little. They have spared us the labour and made us partners in comfort and ease; we fear that they will take away all the reward." The Messenger of Allah (peace and blessings be upon him) said: "No, not as long as you praise them and pray to Allah for them."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 12034