The writer asks this leading question to introduce how he will respond to what Yahweh has done for him. This question can be translated as a statement. AT: "This is how I will repay Yahweh ... to me." (See: [[rc://en/ta/man/translate/figs-rquestion]])
This is probably a reference to a drink offering, which was a sacrifice that involved pouring wine on the altar, and which the writer will offer in response to Yahweh saving him. The full meaning of this statement can be made explicit. AT: "I will present a drink offering to Yahweh because he saved me" (See: [[rc://en/ta/man/translate/figs-explicit]])
The word "Precious" here does not imply that Yahweh values the death of his saints, but that the death of his saints is costly to him and grieves him. Here sight represents judgment or evaluation. AT: "Yahweh considers the death of his saints to be a costly thing" (See: [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-metaphor]])