耶稣说入口的不污秽人，出口的才污秽人。因此，饭吃进自己的肚子，不会弄脏自己，哪怕饭是脏的; 然而从自己口里所出的言语可能会污秽了自己。比如一个人指责，怒骂，嫉恨的言语即出口就污秽了他自己，因为这些言语表明了他心里的恶。看耶稣下面的话。

可7:15 从外面进去的、不能污秽人、惟有从里面出来的、乃能污秽人。〔有古卷在此有〕
There is nothing from outside of the man, that going into him can defile him; but the things which proceed out of the man are those that defile the man.
可7:21 因为从里面、就是从人心里、发出恶念、苟合、
For from within, out of the hearts of men, proceed evil thoughts, adulteries, sexual sins, murders, thefts,
可7:22 偷盗、凶杀、奸淫、贪婪、邪恶、诡诈、淫荡、嫉妒、谤讟、骄傲、狂妄．
covetings, wickedness, deceit, lustful desires, an evil eye, blasphemy, pride, and foolishness.
可7:23 这一切的恶、都是从里面出来、且能污秽人。
All these evil things come from within, and defile the man."