Ibn al 'Arabi uses this phrase quite exactly in his most important prayer, and yet when one reads his words, one doesn't perhaps suspect they have a very precise meaning about a very precise experience. Words always seem to be generalizations; and one can't blame them. Of course, they are, because any report of an experience becomes a generalization by default.
Nonetheless, perhaps they can bring one closer to the experience, to at least an idea of it.
One is impatient. In most cases, one wishes for one impression to be over because the next one is bound to be deeper or more interesting. To be secured is to be within the present moment, under the eye and within the will of God, taking in this particular impression now. In this way, one is a vessel, and one receives; and every other way that one can be, one is not. It is said, one is not, because only in the sense that one is secured does one have being.
The Lord offers mankind the opportunity to be secured. This experience is a substance within the body, and the mind, and the soul; it is a food, not an idea. Within it, the understanding of life and one's position is material. One senses the presence of God, and the Divine Hands that hold us. This is not an imaginary experience; rather, most other experiences are imaginary. There is no image within the Will of God. Security is not an image; it is a condition.
One's lack of trust prevents one's understanding of security within the Will of God. Trust must come from every direction and enter the soul on all sides. Trust must infuse the soul and then emanate back out from it. This Trust is only infused and emanated by Grace itself. All that one does on one's own cannot achieve this Grace. It is, in fact, the very belief that one does anything on one's own that prevents such Grace from penetrating.
So one can stand within one's life and be secured in the Will of God. This is Truth; and Truth is ranked. That is, Truth comes from above, and penetrates downward. So there are superior Truths, and inferior truths, and if a man or woman once tastes a superior Truth, and drinks the sweetness of the Lord, they will understand that they are secured within the Lord.
There is no other kind of security. Every security imagined within the ordinary world and under ordinary conditions is transient and unreliable.
There needs to be an investment, a clothing of the self within the Self. First one is what one is, secure within the Will of God; then one wears the rest of one's Being like a garment.
Truly, without this, there are too many words and ideas, too many fantasies, and too much effort put into imagining. Imagining can be useful; but it begins to grow into something much larger than what is necessary, especially in today's world.
Attention must be more precise and immediate; impressions more intimate. Only within this action is such security to be perceived.
May your soul be filled with light.