Musnad Ahmad 26:637

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Mansur, from Abu Wa'il, from Abdullah, from the Prophet, may Allah bless him and grant him peace, that he said: "A man continues to speak the truth and strives for truthfulness until he is recorded as a truthful one (siddiq). And a man continues to lie and strives for lying until he is recorded with Allah as a liar (kadhdhab)."