Psalm 91 is one of sixteen psalms that are called Messianic Psalms; they are prophetic psalms revealing the Messiah (Christ Jesus) to come. Psalms 2, 8, and 22 are three that you may know.
“Now it came to pass, when men began to multiply on the face of the earth, and daughters were born to them, that the sons of God saw the daughters of men, that they were beautiful; and they took wives for themselves of all whom they chose. And the Lord said, ‘My Spirit shall not strive with man forever, for he is indeed flesh; yet his days shall be one hundred and twenty years.’” Genesis 6:1-3.
“Her [Jerusalem’s] prophets are insolent, treacherous people; her priests have polluted the sanctuary, they have done violence to the law. The Lord is righteous in her midst, he will do no unrighteousness. Every morning He brings His justice to light; He never fails, but the unjust knows no shame.” Zephaniah 3:4-5.
“I have manifested Your name to the men whom You have given Me out of the world. They were Yours, You gave them to Me, and they have kept Your word.” John 17:6.