C. F. Keil and Franz Delitzsch on Proverbs 29:5

Pro 29:5 5 A man who flattereth his neighbour    Spreadeth a net for his steps.

Fleischer, as Bertheau: vir qui alterum blanditiis circumvenit; but in the על there does not lie in itself a hostile tendency, an intention to do injury; it interchanges with אל, Psa 36:3, and what is expressed in line second happens also, without any intention on the part of the flatterer: the web of the flatterer before the eyes of a neighbour becomes, if he is caught thereby, a net for him in which he is entangled to his own destruction (Hitzig). החליק signifies also, without any external object, Pro 28:23; Pro 2:16, as internally transitive: to utter that which is smooth, i.e., flattering. פּעמיו is, as Psa 57:7 = רגליו, for which it is the usual Phoenician word.