Hebrews 5 13
Those who drink baby milk don't have the experience of living the right way—they're just babies.
Compare with other 3 random translations
YLT Hebrews 5:13for every one who is partaking of milk is unskilled in the word of righteousness — for he is an infant,
CSB Hebrews 5:13Now everyone who lives on milk is inexperienced with the message about righteousness, because he is an infant.
EAS Hebrews 5:13Anyone who still thinks like a baby does not yet understand God's message about what is right. It is as if they are still drinking only milk.