Torah Temimah citing Shir ha'Shirim Rabah: Yisrael say, [after the Churban] we do not have the red thread [that used to turn white on Yom Kipur], nor Se'ir ha'Mishtale'ach. Hashem says, the moving of your mouth is dear to Me like the red thread, and your speech is beautiful.

Rashi: They are pleasant to promise and fulfill their promise, like Yehoshua's Meraglim did to Rachav the Zonah. They told her "Es Tikvas Chut ha'Shani ha'Zeh

Rashi: Your Dibur (speech). This is like "ha'Nidbarim Becha Etzel ha'Kiros" (Yechezkel 33:30), "Az Nidberu Yir'ei Hashem" (Mal'achi 3:15).

Seforno: [These are Chachamim who teach] what applies in practice.

Malbim (Melitzah): It is your speech in Torah, Nevu'ah and Ru'ach ha'Kodesh - "Ru'ach Hashem Diber Bi u'Milaso Al Leshoni" (Shmuel II, 23:2).

Rashi citing Brachos 57a: Even the Reikanim (empty) in Yisrael are full of Mitzvos like a pomegranate [is full of seeds].

Rashi: Rakasech is the height of the face, where the jaws protrude by the eyes. The Gemara (Shabbos 64a) calls it Rumani d'Api; it resembles a half pomegranate on the outside. It is red and oval. It is beauty in a woman.

Seforno: Rakasech is [the part of the face] near the mouth; these are the Talmidim. They are full of knowledge of Hashem like a half pomegranate - it has a good taste, even though it is not a full pomegranate.

Malbim (Melitzah): The Nefesh itself is like a half-pomegranate, which has 613 seeds. So the benefit from Hekdesh itself is full of Divine intellectual lights. It is called Rakasech for it does not occupy place. It is like an empty matter in which nothing is found. Even so, it is full like a pomegranate.

Refer to 4:1:3:1-3.

Malbim (Melitzah): We do not understand the Nefesh itself, only based on its tie to the body.