Allah Taala said in the Quran:
[Shakir 81:8] And when the female infant buried alive is asked
[Shakir 81:9] For what sin she was killed,
Shia muhadith ibn Qawlaveyh narrated in his book “al-Kamil az-ziyarat” (p 134):
[3-155] – (Chain) from Abu Abdullah (alaihi salam), which said about words of Allah- : And when the female infant buried alive is asked * For what sin she was killed, – this was revealed about Husayn ibn Ali – alaihuma salam.
So this report is a proof that for them Husayn was female infant!