Musnad Ahmad 30:1485

Hassan narrated to us, Ibn Lahi'ah narrated to us, Abu Yunus narrated to us, from Abu Hurairah, from the Messenger of Allah (peace and blessings of Allah be upon him) that he said: "Would one of you be happy to return to his family with two pregnant she-camels?" They said: "Yes." He said: "Then two verses from the Book that he returns with to his family are better for him than two pregnant she-camels."