Yes, HADITH is a Scrabble word!

Letter values in Scrabble US: H 4, A 1, D 2, I 1, T 1, H 4.

Is it a valid word?

HADITH is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(Islam) a tradition based on reports of the sayings and activities of Muhammad and his companions
(Islam) the way of life prescribed as normative for Muslims on the basis of the teachings and practices of Muhammad and interpretations of the Koran