Musnad Ahmad 174:0

Narrated to us by Yahya ibn Sa’id, from Muhammad ibn ‘Amr, from Abu Salamah, from Khubayb ibn ‘Abd al-Rahman, from his grandfather: A man came to the Prophet (ﷺ) while he was delivering a sermon. He said, "O Messenger of Allah, what is the best of earnings?" He (ﷺ) replied, "A man’s handiwork, provided he is sincere, and every transaction that is free of deception."