Musnad Ahmad 30:3228

Bahz narrated to us, he said: Hammam narrated to us, he said: Qatadah narrated to us, from Abd al-Malik, from Abu Hurairah, that the Prophet, peace and blessings of Allah be upon him, said: "Whoever is presented with something without having asked for it, let him accept it, for it is only a provision that Allah has driven to him."