It is narrated from Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "He has certainly succeeded who accepted Islam, was given provision sufficient for his needs, and was content with what Allah gave him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7868