I lift up my eyes to the hills. From where does my help come?My help comes from the LORD, who made heaven and earth. He will not let your foot be moved; he who keeps you will not slumber. Behold, he who keeps Israel will neither slumber nor sleep. The LORD is your keeper; the LORD is your shade on your right hand. The sun shall not strike you by day, nor the moon by night. The LORD will keep you from all evil; he will keep your life. The LORD will keep your going out and your coming in from this time forth and forevermore. (Psalm 121)
Bible commentators generally agree that this is one of the songs the Jewish people chanted when they were traveling to Jerusalem to the feasts. Jerusalem was the center of their worship, where the temple was located -- and it was in the mountains. So this reference "to the hills" refers to God, as the next verse clarifies.
Despite all our modern ways of communication, people often feel isolated and alone. If we are part of God's family we are never alone. This chapter assures us that God is our help all the time (day or night) and in every situation (your going out and your coming in, despite all evil).
He is never too busy or unaware or asleep! He is not hindered by lack of power (He made heaven and earth). We can be confident that no matter what life may bring our way; He is fully involved in the lives of those who have placed their trust in Him -- both now and into eternity.