So when the night covered him [with darkness], he saw a star. He said, "This is my lord."1 But when it set, he said, "I like not those that set [i.e., disappear]."
Translation: Saheeh International (English)
1 In verses 76-79, beginning from the people's own assertions, Abraham presents a picture of his dissatisfaction as the only logical conclusion one could reach, in order to show them the futility of their false objects of worship.
When the darkness of the night came over Abraham, he began to debate with his people in order to bring them from idolatry to monotheism. His people used to worship the stars, so when he saw a star he said, ‘This is my Lord’, with the aim of convincing his people. When the star disappeared, he said, ‘I do not like that which disappears, because the true God is always present and never disappears’. The belief of his people was that gods do not go away and disappear, so he used this same belief of theirs as an argument against them.