Psalm 121 Shir ha Maalot
1. A song for ascents. I shall raise my eyes to the mountains, from where will my help come?
2. My help is from the Lord, the Maker of heaven and earth.
3. He will not allow your foot to falter; Your Guardian will not slumber.
4. Behold the Guardian of Israel will neither slumber nor sleep.
5. The Lord is your Guardian; the Lord is your shadow; [He is] by your right hand.
6. By day, the sun will not smite you, nor will the moon at night.
7. The Lord will guard you from all evil; He will guard your soul.
8. The Lord will guard your going out and your coming in from now and to eternity

When Tehillim are said with the proper intentions they reach the heaven. Shir ha Maalot Psalm 121 is also said for the recovery of sick people.
According to some Kabbalah resources it is good to have a copy of the Psalm 121 in the delivery room. When a jewish child is born the education towards holiness starts upon birth. This is why we also a copy into the crib, on front of the home and on the doorway of the babys room.