The second is the sleep of mystical death, where she expires in the arms of love.  Neither is He willing she should be disturbed in this, until she awakes of herself by the all-powerful voice of God, summoning her from the tomb of death to the spiritual resurrection.
The third is the slumber of repose in God, permanent, lasting; an ecstatic rest, but sweet, calm and enduring, occasioning no alteration in the senses, the soul having passed into God by her happy deliverance from self. This is a rest from which she shall never be disturbed. He would not that His beloved should be interfered with in any of their slumbers, but that they should be permitted to be at rest, for they sleep in His arms.
The first repose is a promised rest, of which pledges are given; the second is a rest bestowed, and the third is a rest confirmed, whereof there shall be no further interruption. Not that it could not be broken, for she is still at liberty, and the Bridegroom would not say until she please, if she had no longer the power to will it; but after a union of this kind, except we suppose the extremist ingratitude and infidelity, she would never do so.
In the meanwhile the Divine Bridegroom, while He eulogizes His Spouse and permits others to praise her in his presence, desires at the same time continually to instruct her. In order to show her that nothing but a vain self-complacency and contempt of others can give rise to so deplorable a result as a departure from Him, He, in the next verse, sets before her the baseness of her origin and the vileness of her nature, so that she may never lose sight of her humility.