# 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"