Midrasch zu Schemuel II 6:23

He (the king) must not marry more than eighteen wives. Whence is it deduced? From (II Sam. 3, 2-5) And unto David were born sons in Hebron; and his first-born was Ammon, of Achinoam the Zezreelitess; and his second, Chileab, of Abigail, the wife of Nebal the Carmelite; and the third, Abshalom, the son of Maachah, the daughter of Thalmai the king of Geshur; and the fourth, Adonijah, the son of Chaggith; and the fifth, Shepliatiah, the son of Abital: and the sixth, Ithream by Eglah, David's wife. These were born to David in Hebron. And the prophet said (Ib., ib. 12, 8) And if that were too little, then would I add unto thee so much more like these, and like these. Now let us see! The number of the wives mentioned in the Scriptures is six. Like this, is six more; and again, like this, is again six more, of which the total is eighteen. But Michal was also his wife, [and why was she not mentioned]. Rab said: "Eglah is the same as Michal. And why was she named Eglah? Because she was beloved to him just as a calf is beloved to its mother." And so also reads the passage (Judges 14, 18) And he said unto them, if he had not ploughed with my calf, etc. But had, then, Michal children? Is it not written (II Sam. 6, 23) And Michal the daughter of Saul had no child until the day of her death? Said R. Chisda: "Prior to that incident she did have a child, but after that incident she did not have a child." But is it not written (Ib. 5, 13) And David took yet more concubines and wives out of Jerusalem. Hence it is to be supposed that he married more? This was to fulfill the number of eighteen. What are wives, and what are concubines? R. Juda said: "Wives are married by betrothal and marriage contract; concubines are wihtout both of these." R. Juda said in the name of Rab: "Four hundred children were born to David by the handsome captives. They had long locks and sat in golden coaches. They were placed with the chief officers of the military, and were the men of power of the house of David." R. Juda said again: "Thamar was a daughter of one of the [above-mentioned] handsome women, as it is said (II Sam. 13, 13) But now, O speak, I pray thee, unto the king; for he will not withhold me from thee. And if she were really his daughter, how could she say that the king would allow a sister to marry her brother? Infer from this, that she was one of the children born of one of the [above-mentioned] handsome women." (Ib. 13, 3) But Annon had a friend … and Jonadab was a very shrewd man. Said R. Juda in the name of Rab: "A shrewd man to do evil."

... “And David went and he took the bones of Saul and the bones of Jonathan his son from the men of Jabesh- gilead… And he brought up from there the bones of Saul and the bones of Jonathan his son…” (Shmuel II 21:12-13) What did David do? He went and gathered all the elders and great ones of Israel, crossed the Jordan River, and came to Yavesh-gilead. He found the bones of Shaul and his son Yonatan, placed them in a casket and crossed back over the Jordan, as it says “And they buried the bones of Saul and Jonathan his son in the country of Benjamin in Zela, in the tomb of Kish his father and they did all that the king commanded…” (Shmuel II 21:14) What does ‘in Zela, in the tomb of Kish his father’ mean? It comes to teach us that they brought them to the border of Jerusalem and buried them there. Zela is next to Jerusalem, as it says “And Zelah, Eleph, and the Jebusite, which is Jerusalem…” (Yehoshua 18:28) ‘and they did all that the king commanded’ And what did the king command? He commanded that they carry Shaul’s casket from tribe to tribe. As Shaul’s casket entered each tribe’s territory all the men, women and children came out in order to perform an act of loving kindness to Shaul and his sons and thereby all of Israel would fulfill its obligation to loving kindness. This went on until they reached the land of his portion on the border of Jerusalem. Since the Holy One saw that they did loving kindness to Shaul and fulfilled the judgement of the Givonites He was immediately filled with mercy and sent rain upon the land, as it says “And God was entreated for the land after that.” (Shmuel II 21:14) From this we learn how close the Holy One brings those that are far away, even though they converted not for the sake of heaven. There is no need to even mention how he draws near righteous converts, “O Lord, all the kings of the earth will acknowledge You…” (Tehillim 138:4)