Musnad Ahmad 27:674

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Simak, from Mus'ab ibn Sa'd, who said: Ibn 'Amir became ill, and they began to praise him, while Ibn 'Umar was silent. He (Ibn 'Umar) said: "As for me, I am not the most deceitful of them toward you, but the Messenger of Allah (ﷺ) said: 'Indeed, Allah does not accept prayer without purification, nor charity from spoils of war (obtained through treachery).'"