Answer:
He was planning to have one himself, so he began with a polite offer to the blind man.
Explanation:
The husband and his wife occasionally smoke marijuana as a way to relax at night. Now that the blind man was visiting them, he didn't want to change his habits and he felt like smoking a cigarette at the time. As he wanted one, he also offered it to the blind man - that's all there's to it as there were no bad intentions.
