What does Robinson's patron order him to do that allows for his escape?

Robinson's patron orders him to go fishing as usual, even though, he had never been allowed to fish alone (the patron always accompanied him). This order enabled his escape.

He told Robinson "his guests had put off going from some business that fell out, and ordered me, with the man and boy, as usual, to go out with the boat and catch them some fish, for that his friends were to sup at his house, and commanded that as soon as I got some fish I should bring it home to his house; all which I prepared to do.
This moment my former notions of deliverance darted into my thoughts, for now I found I was likely to have a little ship at my command; and my master being gone, I prepared to furnish myself, not for fishing business, but for a voyage; though I knew not, neither did I so much as consider, whither I should steer - anywhere to get out of that place was my desire."