May it fall: technically the pronoun it in Revised Standard Version refers back to the blood of Abner. The Hebrew is literally “May they [the bloods] fall.” As in Josh 2.19 the expression “his blood shall be on his head” is a way of saying “he is responsible for his own death” (see also 2 Sam 1.16). Here David is saying that it was Joab who was responsible for Abner’s death, and that it is therefore Joab who should be punished.
The head of Joab: the head represents Joab himself. In view of the special expression just discussed, the idiom should be translated as a whole, and it will be unnecessary in most cases to retain the word head in translation.
All his father’s house … the house of Joab: as previously (1.12; 2.4; 3.1), the word house stands for the families of the persons mentioned. Here David pronounces what amounts to a curse on the members of Joab’s family. He lists five different kinds of misery that often occurred in the ancient world, and he wishes them on the family and descendants of Joab.
Never be without: some languages will use the negative of the verb “lack” at this point. However, this can be stated positively as “always be with” or “always have,” depending on the particular structure of the receptor language rendering.
Discharge: this physical infirmity is treated in detail in Lev 15. The Hebrew word rendered one who has a discharge has the same root as the verb translated “flowing” in Exo 3.8, 17; 13.5; 33.3. This usually refers to the abnormal flow of fluid from the male sexual organ as a result of some kind of sickness. Good News Translation therefore makes it specifically “gonorrhea,” while Revised English Bible speaks here more generally of “a running sore.” Such a discharge made a man ritually unclean (see Lev 15.2-15).
Leprous: the disease usually translated as “leprosy” is frequently mentioned in both the Old and New Testaments (see especially Lev 13–14, where the laws concerning this disease are given). While most versions translate this word as leprous, they usually provide footnotes or glossary entries explaining that leprosy in the Bible is not the same as what we call by that name today. It referred rather to a group of skin disorders that cannot be positively identified today. For this reason Good News Translation speaks of a “dreaded skin disease.”
The important point concerning both the discharge and the “dreaded skin disease” is that these diseases made one ritually unclean. David is not simply wishing any illnesses on Joab’s descendants. Rather these are illnesses that affect one’s standing in the religious community. Translators may wish to follow Parola Del Signore: La Bibbia in Lingua Corrente in making this information explicit: “May there always be someone in the family of Joab struck by sicknesses that make one ritually unclean.”
Who holds a spindle: since the word translated spindle usually refers to the instrument used by women to spin thread (see Pro 31.19), most versions have taken this to mean that David was wishing that there would always be “one unmanly” (New American Bible) or “some effeminate creature” (Moffatt) among the descendants of Joab. Contemporary English Version says “May they all be cowards.” Some interpreters understand the Hebrew to mean that some men would be eunuchs, and this interpretation is reflected in the Nueva Biblia Española rendering “castrated.” Compare Good News Translation “fit only to do a woman’s work,” and Parola Del Signore: La Bibbia in Lingua Corrente “forced to do women’s work.”
Several versions, however, including the Septuagint, take the word to refer to a stick used to help a lame person walk, and therefore translate “who must lean on a crutch” (New Century Version), “who leans on a crutch” (New International Version), and “clings to a crutch” (Anchor Bible).
Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on the First and Second Books of Samuel, Volume 2. (UBS Helps for Translators). New York: UBS, 2001. For this and other handbooks for translators see here .