en_tn_condensed/ezk/44/12.md

became stumbling blocks for sin for the house of Israel

"became people who caused the house of Israel to sin"

I will lift up my hand to swear an oath

"I will solemnly swear". A person would raise his right hand to show that he realized that God would punish him if he did not do what he swore to do. See Ezekiel 20:6.

against them

"that I will punish them"

this is the Lord Yahweh's declaration

"this is what I, the Lord Yahweh, have declared". Yahweh speaks of himself to express the certainty of what he is declaring. See Ezekiel 5:11.

they will bear their punishment

"I will certainly punish them"