Now the Lord spoke to Moses and Aaron, saying, “This is the ordinance of the law which the Lord has commanded, saying: ‘Speak to the children of Israel, that they bring you a red heifer without blemish, in which there is no defect and on which a yoke has never come. You shall give it to Eleazar the priest, that he may take it outside the camp, and it shall be slaughtered before him; and Eleazar the priest shall take some of its blood with his finger, and sprinkle some of its blood seven times directly in front of the tabernacle of meeting. Then the heifer shall be burned in his sight: its hide, its flesh, its blood, and its offal shall be burned. And the priest shall take cedar wood and hyssop and scarlet, and cast them into the midst of the fire burning the heifer. Then the priest shall wash his clothes, he shall bathe in water, and afterward he shall come into the camp; the priest shall be unclean until evening. And the one who burns it shall wash his clothes in water, bathe in water, and shall be unclean until evening. Then a man who is clean shall gather up the ashes of the heifer, and store them outside the camp in a clean place; and they shall be kept for the congregation of the children of Israel for the water of purification; it is for purifying from sin. And the one who gathers the ashes of the heifer shall wash his clothes, and be unclean until evening. It shall be a statute forever to the children of Israel and to the ger who dwells among them.
What Does It Say?
Numbers 19 lists a number of different purification rituals. I'm not going to go into the precise situations; they're in your Bible, just read it.
Two things stick out in chapter 19. The first is that this initial ritual for creating the water of purification is the only one which specifically mentions ger. This indicates that a ger could take part in this ritual in the temple - not as a priest, but perhaps as the one who gathers the ashes. Presumably, the other rituals of purification are also incumbent on any ger in the land (though again, this is not explicitly stated).
Second, the further rituals of purification in chapter 19 explicitly state that:
But the man who is unclean and does not purify himself, that person shall be cut off from among the assembly [qahal], because he has defiled the sanctuary of the Lord. The water of purification has not been sprinkled on him; he is unclean.
- Numbers 19:20Verse 13 has a similar curse on those who do not purify themselves, except it says they will be cut off "from Israel." Thus the one who does not abide by the law of the Lord is even lower than a ger.
Next: Numbers 35