Tabari mentioned in his famous book of history Tareekh al-Tabari (V. 8, P.187) that Yazeed openly declared his infidelity and denying Islam when he saw the head of Imam Husain (AS) by saying:
لعبت هاشم بالملك فلا. خبرٌ جاء ولا وحيٌ نزل
Hashim family (of the Prophet) played with rule, otherwise, nothing came from God, nor any revelation was sent.
This poem of the cursed Yazeed is narrated in many other Sunni books.