Isaiah 30:1 reads,
“Woe, rebellious sons, utterance of Yahweh, who make a plan, but not from me, who pour out a libation [i.e., make an alliance], but not of my Spirit, so as to add sin to sin.”
In response to the threats they face, rather than trusting Yahweh and relying on the guidance of his Spirit, Israel resorts to her own schemes, striking deals with other nations that involve pouring out libations to the gods those nations worship.
If the words “who pour out a libation” are done with the dynamic equivalent “make an alliance,” it is much harder for the reader who only has English to understand the problem. But if the words “who pour out a libation” are included, readers are tipped off to the fact that the alliance was made possible by Israel’s willingness to engage in idolatry.