R. Yonah #1: After discussing quarrels, the verse comes to disdain them. Due to quarrels, a man sins with his lips with Leshon ha'Ra and Rechilus. He will be punished for the fruits of his mouth and lips, just like he is punished for deeds.

R. Yonah #2: A man's reward for the words of his mouth is increased if he rebukes the Rabim and brings merit to them, or makes Shalom between friends, or teaches Torah. The Reisha discusses the punishment for Leshon ha'Ra ¹ , and the Seifa discusses the reward for a Tzadik's tongue. "Pri" can refer also to punishment - "Pri Machshevosam" (Yirmeyah 6:19). The coming verse "Maves v'Chayim b'Yad ha'Leshon" explains this one.

Malbim: The mouth hints to speech with Chachmah. The lip hints to Da'as. When one speaks Chachmah with his mouth, it yields fruits to the point that his stomach is satiated. Tevu'ah is finished fruit; it is a metaphor for Da'as. Then, he knows the laws of Chachmah with clear knowledge. He speaks it with his lips - external speech, the Tevu'ah of the fruits. Then he is satiated a second time from the Tevu'ah of Da'as. He eats Chachmah and Da'as and is satiated. When he is satiated, he need not eat more, for they are received matters. "V'Ozen Chachamim Tevakesh Da'as" (15); when it receives, it is satiated and will not eat more.

Malbim (13:2): His stomach will be satiated from the fruits of his mouth (Chachmah), for good or for bad, according to the preparation. From it, he will be satiated with bread.

Malbim (13:2): Da'as (clear knowledge) is the finished grain.