The 150th prohibition is that we are forbidden to consume ma'aser sheni in a state of tumah — even in Jerusalem — unless it has been redeemed. This corresponds to the general principle that ma'aser sheni which has become tameh must be redeemed, even in Jerusalem, as explained in tractate Makos.1

The source of this prohibition is the verse,2 "I have not consumed in a state of tumah." The Oral Tradition3 explains [the phrase "in a state of tumah"] — "either when I was tameh and it was tahor, or when I was tahor and it was tameh."

In Gemara Makos it is also explained that ma'aser and bikurim may not be eaten in a state of tumah; and that one who does so is punished by lashes. As mentioned above, lashes are given only when this ma'aser is eaten in a state of tumah, in Jerusalem and was not redeemed.