what is robinson ordered to do thats gives him the opportunity to escape?

Robinson's patron (the man who held him captive) took him fishing regularly, but never allowed him to go alone. They were always together. Then one day, something else came up, and he was told to go fishing as usual and deliver the fish back at the house..............

They'd been getting a ship ready for a voyage, and Robinson made a last moment decision to take his fishing mates and the ship. He had the opportunity and he took it!

"I got all things ready as he had directed, and waited the next morning with the boat washed clean, her ancient and pendants out, and everything to accommodate his guests; when by-and-by my patron came on board alone, and told me 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."