First Lessons in Maori
Because is generally expressed by ta te mea or no te mea, but if the reference is to an antecedent moving cause the preposition na may be used followed by a relative clause (§ 73).
E kore ahau e riri ki a koe, ta te mea e aroha ana ahau ki a koe, I will not be angry with you, because I love you.
Ka riri a Huakatoa, no te mea i rukea e ratou nga kai, Huakatoa was angry because they threw away the food.
Na te kino hoki i mahue ai te whenua, Because of its badness the land was abandoned.
Na reira i tika ai ta ratou heke mai, On that account they departed forthwith.