Numbers 19:!-22..Now the Lord spoke to Moses and to Aaron, saying, “This is the statute of the law that the Lord has commanded: Tell the people of Israel to bring you a red heifer without defect, in which there is no blemish, and on which a yoke has never come. And you shall give it to Eleazar the priest, and it shall be taken outside the camp and slaughtered before him. And Eleazar the priest shall take some of its blood with his finger, and sprinkle some of its blood toward the front of the tent of meeting seven times. And the heifer shall be burned in his sight. Its skin, its flesh, and its blood, with its dung, shall be burned. ...
There is a rather long list of verses that you can find here:
What Does the Bible Say About The Red Heifer?
Some of the verses might just refer to 0 he "heifer" but the implication is the red heifer based on the context.