allamah Taftazani on Yazid.

[Abu Rumaysah]

as Salam Alaykum.

Shaykh al-allamah Sa'ad al-Din Masud ibn Umar ibn Abd Allah al-Taftazani (Persian: سعدالدین مسعودبن عمربن عبداللّه هروی خراسانی تفتازانی‎) said in his commentary on Aqaid an-Nasafiyah (Creed of Imam Nasafi):

 - However, they [that is, the Fathers and the Learned] differed so about Yazid b. Mu'awiya [whether cursing him was permissible or not] that it was stated in al-Khuldsa and other books that it was not fitting to curse him nor al-Hajjaj, since the Prophet prohibited the cursing of those who performed worship and who are of the people of the qibla. As
for that which has been reported about the Prophet's cursing some of the people of the qibla, that was because he knew things about the affairs of men which no one else knew. Some pronounced a curse on Yazid because he became
an Unbeliever when he ordered the murder of al-Husayn. They agreed to permit the cursing of those who killed al-Husayn, or commanded it, or permitted it, or consented to it. The real fact is that the consent of Yazid to the killing of al-Husayn, his rejoicing in it, and his contempt for the family of the Prophet are among those things the meaning of which is based on tawatur although the details of the incident are from individual traditions. So then we do not hesitate at all concerning him, rather we do not hesitate [to decide] about his Belief [as to whether he had any or not] the curse of Allah on him, his Helpers, and his Allies. (end of quote)

Source: Taftazani "A Commentary on the Creed of Islam" p 154-155. Translated by Earl Edgar Elder.