Musnad Abu Ya'la al-Mawsili 153:214

Ubayd Allah ibn Umar al-Qawariri narrated to us, Hammad narrated to us, from Amr, he said: Hammad and Layth [narrated] from Amr, from Ibn Umar, raising it to the Prophet, may Allah bless him and grant him peace, he said: "Do not be importunate in asking, for whoever extracts something from it [the people] through it, it will not be blessed for him."