Numbers 19:15

And every open vessel ,.... An earthen one, as the Targum of Jonathan; and so Jarchi interprets it; and Maimonides F18 In Misn. Cholin, c. 1. sect. 6. observes, that this is only to be understood of an earthen vessel:

which hath no covering bound upon it ; a linen or a woollen cloth wrapped and tied about it:

is unclean ; the air of the house getting into it by its being uncovered.