Apocalypse Revealed #377
377. So he said to me, "These are ones who are coming out of the great tribulation." This symbolically means that they are people who have undergone temptations or trials, and have fought against evils and falsities.
To be shown that tribulation means an infestation by evils and falsities and a spiritual battle against them, which is a temptation or trial, see nos. 33, 95, 100, 101.
Exodus 30:18-21
18
"You shall also make a basin of brass, and its base of brass, in which to wash. You shall put it between the Tent of Meeting and the altar, and you shall put water in it.
19
Aaron and his sons shall wash their hands and their feet in it.
20
When they go into the Tent of Meeting, they shall wash with water, that they not die; or when they come near to the altar to minister, to burn an offering made by fire to Yahweh.
21
So they shall wash their hands and their feet, that they not die: and it shall be a statute forever to them, even to him and to his descendants throughout their generations."