"on the land whither you are coming to inherit it": in reward for your coming, you will inherit.
(Devarim 23:22) "If you make a vow to the L-rd, you shall not delay to pay it": It is written here "a vow," and elsewhere (Vayikra 7:16) "a vow." Just as there, "a vow or a pledge (nedavah)," so, here, a vow or a pledge. And just as with the vow here, "you shall not delay to pay it," so, with the vow there, you shall not delay to pay it.