Bellarmine on Psalm 120 : verse 4

Verse 4

Behold he shall neither slumber nor sleep, that keepeth Israel.

Ecce non dormitabit neque dormiet qui custodit Israel.

The Prophet promises the pilgrim will obtain the grace he was asking for, as though to say: I pray that the Father who took you into His care will not slumber; there is no doubt He will not fall into a sleep; for He who watches over His own people never falls asleep nor slumbers; Israel stands for His own people and yet includes all the people in the world who turn and hasten to go up to the heavenly city. When it says “He shall neither slumber nor sleep,” the meaning is this, He will not doze by closing His eyes and then opening them: much less will he give Himself into a deep sleep; and so He will be ever watchful, not closing His eyes for a moment. St. Augustine puts it beautifully when he says men doze when they have bodily weakness and they fall asleep when they are dying;  the watchfulness of men, therefore, is not to be trusted; but we can safely believe in the Lord, who is a most faithful guardian, for he neither slumbers in weakness nor falls into sleep when dying. St. Augustine correctly notes that Israel is to be understood as referring to faithful men, because Israel is interpreted as (men) seeing God, and the faithful never see God through faith,[1] but after (this earthly life), they will see Him.[2]

[1] Who only hath immortality, and inhabiteth light inaccessible, whom no man hath seen, nor can see: to whom be honour and empire everlasting. Amen. qui solus habet immortalitatem, et lucem inhabitat inaccessibilem : quem nullus hominum vidit, sed nec videre potest : cui honor, et imperium sempiternum. Amen. [I Timothy vi. 16]

[2] We see now through a glass in a dark manner; but then face to face. Now I know in part; but then I shall know even as I am known. Videmus nunc per speculum in aenigmate : tunc autem facie ad faciem. Nunc cognosco ex parte : tunc autem cognoscam sicut et cognitus sum. [I Corinth. Xiii. 12] 

Totus tuus ego sum

Et omnia mea tua sunt;

Tecum semper tutus sum:

Ad Jesum per Mariam.