1)
Why does he ask Hashem to pass his eyes from seeing futility?
1.
Radak: It is to help him to fulfill the Mitzvos. If he sees Shav, perhaps he will veer after it.
2.
Malbim: This refers to the previous verse - my eyes should not see reward and Batza; I should not put my heart on this, rather, on the ways themselves.
2)
Why did he say "Chayeni"?
1.
Radak: Sin kills a person.
2.
Malbim: Enable me to see that Hashem's ways are Chesed, mercy and Chaninah, and I will learn to go in His ways to live in them.
