The Hebrew that is translated as “Saul has killed his thousands; and David his tens of thousands” or similar in English is translated in Falam Chin as “Saul killed by the hundreds, David killed by the thousands.”
Stephen Hre Kio explains (in The Bible Translator 1990, p. 210ff.):
“While translating the book of 1 Samuel, we came across a number of verses (18:7; 21:11; 29:5) where people sang praises to David for his skill in killing the Philistines. The people sang: ‘Saul has slain his thousands, and David his ten thousands.’ I asked myself: Did the people of Israel actually count the bodies killed by Saul (thousands) and by David (ten thousands) at every place where battles had taken place? It was very doubtful to me that they did it. It seemed more likely that they sang this song with a figurative meaning: that is, David had killed ten times more than Saul had, without any thought for the exact numbers. Being figurative it was not necessary that we translate the verse literally; adjustment could be made if necessary without being unfaithful to the text. Compelling us in this direction was also the fact that in the Falam language it would be unnatural to translate the above song literally. It would be funny to sing it. So we changed it to read ‘hundreds’ and ‘thousands’:
‘Saul killed by the hundreds,
David killed by the thousands.’
“Fortunately there is even an internal rhyme in this verse in Falam. And the figurative meaning of David killing ‘ten times’ more than Saul did is kept. This, in my view, is an acceptable translation in spite of the adjustment made. The principle of making an appropriate adjustment in figurative language without being unfaithful to the text seems to be true in this case also.”
See also 1 Samuel 18:8.