Let them wander up and down for meat - Let them be like dogs that wander about for food, and find none. The idea is, that they would not find him, and would be then as dogs that had sought in vain for food.
And grudge if they be not satisfied - Margin, If they be not satisfied, then they will stay all night. The marginal reading is most in accordance with the Hebrew. The sentence is obscure, but the idea seems to be that they would not be satisfied - that is, they would not obtain that which they had sought; and, like hungry and disappointed dogs, they would be compelled to pass the night in this miserable and wretched condition. The word which our translators have rendered "grudge" - from לוּן lûn - means properly to pass the night; then, to abide, to remain, to dwell; and then, in Hiphil, to show oneself obstinate and stubborn - from the idea of remaining or persisting in a bad cause; and hence, the word sometimes means to complain: Numbers 14:29; Exodus 17:3. It has not, however, the signification of grudging, though it might mean here to murmur or complain because they were disappointed. But the most natural meaning is that which the word properly bears - that of passing the night, as referring to their wandering about, disappointed in their object, and yet still hoping that they might possibly obtain it. The anticipated feeling in the mind of the psalmist is that which he would have in the consciousness of his own safety, and in the pleasure of knowing that they must sooner or later find out that their victim had escaped.

Let them wander up and down for meat,.... Like hungry dogs;
and grudge if they be not satisfied; or murmur and howl as dogs when hungry, and can find nothing to eat; or "when they shall not be satisfied, and shall lodge" (z); when they shall get nothing to satisfy their hungry appetite, and shall go to bed without a supper, and lie all night without food. The Targum is,
"they shall wander about to seize the prey to eat, and will not rest till the are satisfied, and will lie all night;''
that is, in quest of prey.
(z) "nec satiati cubabunt", Tigurine version; "famelici pernoctabunt", Michaelis.

grudge if, &c.--literally, "they shall stay all night," that is, obtain nothing.