R. Yonah: After mentioning flattery "Meradef Amarim" (7), he comes to warn about acquiring good Midos. One who loves his Nefesh, he acquires good Midos, for the attribute of the Nefesh is according to its Midos. Kinyan ha'Lev is the Kinyan of Midos - "v'Shome'a Tochachas Koneh Lev" (15:32).

Malbim: The heart is the power that rules in man. Also one who knows the laws of Chachmah, still, the heart is not his, for desire and Chachmah fight in his heart. The Yetzer builds great fortresses to conquer the heart under its rule. One who loves his Nefesh and wants to guard it lest the enemy cut it off. He acquires the heart - "b'Lev Navon Tanu'ach Chachmah" (14:32). Via contemplation of the ways of Chachmah with the power of Tevunah, to understand its reasons, the war will depart and the heart will be in his Reshus. This is called Koneh. Tevunah is like money with which one buys merchandise - "u'Kenos Binah Nivchar mi'Kasef" (16:16).

R. Yonah: When one contemplates in his heart a matter of Tevunah, and is Mechadesh a nice matter or hears it from another, he guards it to his heart and is diligent to remember it, to carry it out in deed. In this way, man acquires good Midos and finds good.

Malbim: He acquires the heart via guarding Tevunah. Since sometimes one requests evil via Binah, and he understands in fake ways and finds false mindsets, there is a condition in guarding Tevunah in order to find good - refer to 19:9:1:2.