Your eye shall not pity him: this is a vivid way of expressing lack of pity. Where there is a good idiomatic phrase for such a feeling, it should be used. See its use in 13.8.

Purge the guilt of innocent blood from Israel: a deliberate murder defiled the land, and it had to be cleansed. This could be achieved only by executing the murderer (see Num 35.33-34). For the verb purge see 13.5. Since the idea of “cleansing” may not be natural in this context, something like “get rid of,” “remove,” “take away” can be used. Some translations, like Good News Translation, Bible en français courant, Nova Tradução na Linguagem de Hoje, have “get rid of murderers,” but this does not really represent the meaning of the text, which is speaking not about murderers but about the land as such, which had been defiled or soiled by the spilling of innocent blood (see Gen 4.10-11). In languages where the idea of guilt of innocent blood will be difficult to translate, we may say something like “rid [or, remove from] the land of the blood of innocent people who have been murdered,” or “clear the name [or, face; or, reputation] of the people of Israel for the innocent people who….”

That it may be well with you: see 4.40.

Quoted with permission from Bratcher, Robert G. and Hatton, Howard A. A Handbook on Deuteronomy. (UBS Helps for Translators). New York: UBS, 2000. For this and other handbooks for translators see here .