"Way" may be understood either literally (compare Ecclesiastes 10:15), or figuratively, of the course of action which he follows.
He saith - He exposes his folly to every one he meets.

When - a fool walketh by the way - In every act of life, and in every company he frequents, the irreligious man shows what he is. Vanity, nonsense, and wickedness are his themes: so that in effect he saith to every one that he is a fool.

Also, when he that is a fool walketh by the way, his wisdom faileth [him], and he (b) saith to every one [that] he [is] a fool.
(b) By his doings he betrays himself.

Yea also, when he that is a fool walketh by the way,.... The king's highway, the common road; as he passeth along the streets, going to any place, or about any business:
his wisdom faileth him; or "his heart" (p); he appears by his gait, his manner of walking, to want a heart, to be a fool; walking with a froward mouth, winking with his eyes, speaking with his feet, and teaching with his fingers; all which shows the frowardness and folly of his heart, Proverbs 6:12; or he discovers it throughout his conversation, in all the actions of it, in whatsoever business he is concerned, and in all the affairs of life. The Targum is,
"when he walketh in a perplexed way;''
then his wisdom fails him; he does not know which way to take, whether to the right or left: this can never be understood of the highway of holiness, in which men, though fools, shall not err, Isaiah 35:8;
and he saith to everyone that he is a fool; his folly is manifest to all; he betrays it, by his words and actions, to every man he has to do with; his sins and transgressions, which are his folly, he hides not, they are evident to all; and, as the Targum expresses it,
"all say he is a fool:''
though indeed he himself says this of every other man, that he is a fool; for, according to the Vulgate Latin version, he, being a fool himself, thinks everybody else is so.
(p) "cor ejus", Pagninus, Montanus, &c.

by the way--in his ordinary course; in his simplest acts (Proverbs 6:12-14). That he "saith," virtually, "that he" himself, &c. [Septuagint]. But Vulgate, "He thinks that every one (else whom he meets) is a fool."

This proverb forms, along with the preceding, a tetrastich, for it is divided into two parts by vav. The Kerı̂ has removed the art. in כש and שה, Ecclesiastes 6:10, as incompatible with the ש. The order of the words vegam-baderek keshehsachal holek is inverted for vegam keshehsachal baderek holek, cf. Ecclesiastes 3:13, and also rav shěyihyn, Ecclesiastes 6:3; so far as this signifies, "supposing that they are many." Plainly the author intends to give prominence to "on the way;" and why, but because the fool, the inclination of whose heart, according to 2b, always goes to the left, is now placed in view as he presents himself in his public manner of life. Instead of לב־הוּא חסר we have here the verbal clause חסר לבּו, which is not, after Ecclesiastes 6:2, to be translated: corde suo caret (Herzf., Ginsb.), contrary to the suff. and also the order of the words, but, after Ecclesiastes 9:8 : cor ejus deficit, i.e., his understanding is at fault; for לב, here and at Ecclesiastes 10:2, is thus used in a double sense, as the Greek νοῦς and the Lat. mens can also be used: there it means pure, formal, intellectual soul-life; here, pregnantly (Psychol. p. 249), as at Ecclesiastes 7:7, cf. Hosea 4:11, the understanding or the knowledge and will of what is right. The fool takes no step without showing that his understanding is not there, - that, so to speak, he does not take it along with him, but has left it at home. He even carries his folly about publicly, and prides himself in it as if it were wisdom: he says to all that he is a fool, se esse stultum (thus, correctly, most Jewish and Christian interpreters, e.g., Rashi and Rambach). The expression follows the scheme of Ps. 9:21: May the heathen know mortales se esse (vid., l.c.). Otherwise Luther, with Symm. and Jerome: "he takes every man as a fool;" but this thought has no support in the connection, and would undoubtedly be expressed by המּה סכלים. Still differently Knobel and Ewald: he says to all, "it is foolish;" Hitzig, on the contrary, justly remarks that סכל is not used of actions and things; this also is true of כּסיל, against himself, Ecclesiastes 5:2, where he translates qol kesil by "foolish discourses."

Walketh - In his daily conversation. He saith - He discovers his folly to all that meet him.