Ahitophel ("Brother of Insipidity", or "Impiety") was a counselor of King David and a man greatly renowned for his sagacity. At the time of Absalom's revolt he deserted David (Psalm. 41:9; 55:12-14) and espoused the cause of Absalom (2 Samuel 15:12).
David sent his old friend Hushai back to Absalom, in order that he might counteract the counsel of Ahitophel (2 Sam. 15:31-37). Ahitophel, seeing that his good advice against David had not been followed due to Hushai's influence, correctly predicted that the revolt would fail. He then left the camp of Absalom at once. He returned to Giloh, his native place, and after arranging his worldly affairs, hanged himself, and was buried in the sepulcher of his fathers (2 Sam. 17:1-23).
It would seem from a conjunction of II Sam, 23:34, and 11:3, that Ahitophel was the grandfather of Bathsheba, and it has been suggested, as an explanation of his conduct towards David, that he had kept a secret grudge against the King for the way he had treated Bathsheba, and her first husband, Urias. This, or some motive of ambition, would be in keeping with the haughty character of Ahitophel.
In Rabbinical Literature:
The Talmud speaks of this councilor of David as "a man, like Balaam, whose great wisdom was not received in humility as a gift from heaven, and so became a stumbling-block to him" (Num. R. xxii.). He was "one of those who, while casting longing eyes upon things not belonging to them, lose also the things they possess" (Tosef., Soṭah, iv. 19). Ahithophel was initiated into the magic powers of the Holy Name, by means of which he could replace the foundation-stone of the world, removed by King David in his search for the great abyss, in the exact spot above which the Temple was to be built. And being thus familiar with all the secret lore as imparted through the Holy Spirit, he was consulted as an oracle like the Urim we-Tummim (II Sam. xvi. 23, Yer. Sanh. x. 29a, Suk. 53a et seq.). But he withheld his mystic knowledge from King David in the hour of peril, and was therefore doomed to die from strangulation (Tanna debe Eliyahu R. xxxi., Mid. Teh. iii. 7; Ex. R. iv., Mak. 11a). "Ahitophel of the house of Israel and Balaam of the heathen nations were the two great sages of the world who, failing to show gratitude to God for their wisdom, perished in dishonor. To them the prophetic word finds application: 'Let not the wise man glory in his wisdom,' Jer. ix. 23" (Num. R. xxii.). Socrates was said to have been a pupil of his. K.
The Haggadah states that Ahithophel, who was the grandfather of Bath-sheba (Sanh. 69b), was misled by his knowledge of astrology into believing himself destined to become king of Israel. He therefore induced Absalom to commit an unpardonable crime (II Sam. xvi. 21), which sooner or later would have brought with it, according to Jewish law, the penalty of death; the motive for this advice being to remove Absalom, and thus to make a way for himself to the throne. His astrological information had been, however, misunderstood by him; for in reality it only predicted that his granddaughter, Bathsheba, the daughter of his son Eliam, would become queen (Sanh. 101b, YalḲ. Sam. § 150). David, during his reign, had many disagreeable encounters with Ahithophel. Shortly after his accession the king seems to have overlooked Ahithophel in his appointments of judges and other officials. Consequently, when David was in despair concerning the visitation upon Uzzah during the attempted transport of the ark (II Sam. vi. 6; see Uzzah) and sought counsel of Ahithophel, the latter mockingly suggested to him that he had better apply to his own wise men. Only upon David's malediction, that whoever knew a remedy and concealed it should surely end by committing suicide, did Ahithophel offer him some rather vague advice, concealing the true solution, which was that the ark must be carried on the shoulders of men instead of upon a wagon (Num. R. iv. 20, Yer. Sanh. x. 29a).
Curse upon Ahithophel.
Ahithophel rendered a service to David upon another occasion; not, however, until he had been again threatened with the curse. It appears that David excavated too deeply for the foundations of the Temple, with the result that earth's deepest floods () broke forth, and nearly inundated the earth. None could help but Ahithophel, who withheld his counsel in the hope of seeing David borne away upon the flood. When David again warned him of the malediction, Ahithophel counseled the king to throw a tile, with the ineffable name of God written upon it, into the cavity; whereuponthe waters began to sink. Ahithophel is said to have defended his use of the name of God in this emergency by reference to the practise enjoined by Scripture (Num. v. 23) to restore marital harmony; surely a matter of small importance, he argued, compared with the threatened destruction of the world (Suk. 53a, b). David's repeated malediction that Ahithophel would be hanged was finally realized when the latter hanged himself.
Ahithophel's death was a great loss to David; for his wisdom was so great that Scripture itself (II Sam. xvi. 23) avoids calling him a man; in the passage quoted the Hebrew word for man, , is omitted in the text, being supplied only by the Masorah. Indeed, his wisdom bordered on that of the angels (Yer. Sanh. x. 2; YalḲ. II Sam. § 142). His learning in the Law was also extensive, so that David did not scruple to call him "master" (Abot, vi. 2; the two things which David is there said to have learned from Ahithophel are more closely described in "Kallah," 16a (ed. N. Coronel). Ahithophel's disposition, however, was a jealous one; and he always sought to wound David by mocking remarks (PesiḲ. ii. 10b; Midr. Teh. iii. 3, and parallel passages in Buber, note 68). His devotion to the study of the Law was not founded on worthy motives (Sanh. 106b). Ahithophel was thirty-three years old when he died (l.c.). In his will he left warning to his children never to side against the royal Davidic family, and to take no part in their dissensions (Yer. l.c.). Ahithophel is counted among those that have no share in the world to come (Sanh. xi. 1; B. B. 147a). L. G. 
This entry incorporates text from the public domain Easton's Bible Dictionary, originally published in 1897.