Kommentar zu Bereschit 49:17

שפיפן is another name for a נחש. I am of opinion that it is thus called because it hisses (נושף) when biting. Similarly we have, (Genesis 3:15) “and thou shalt bite (תשיפנו) at their heel” (cf. Rashi thereon).

SH’PHIPHON (SERPENT)¹⁹²Verse 17 here: Dan shall be a serpent by the way, a ‘sh’phiphon’ on the path, that biteth the horse in the heels, so that his rider falleth backward. is the name of a snake which bites at the heel, with the second root-letter¹⁹³Namely, the pei. being doubled.¹⁹⁴Ramban is suggesting that the root of sh’phipon is shapha which means “hissing while biting,” except that the letter pei is here doubled. In the Jerusalem Talmud, Tractate Terumoth¹⁹⁵8:3. the Rabbis said, “It is a small kind of serpent, its name is sh’phiphon, and it is as thin as a hair,” with the earth being permitted to crack before it. Samson is compared to a snake because Samson did not wage war against his enemies as did the other judges and kings. Rather he alone went out against them, just as the viper which leaves his hole to attack travellers on the road, or the small species of serpent of which the traveller is not at all aware.

יהי דן נחש, a reference to a poisonous snake, one commonly called tzifoni, in Biblical literature. Arab physicians usually call such venomous snakes chorman. The name for such snakes implies that a single snake can kill numerous people at once, using both its stare, and it voice (hiss) which is heard and seen by many people. It is a fitting comparison to Shimshon who, all on his own, killed many people almost simultaneously.