For thy servant’s sake: David’s prayer continues with a third person reference to himself here, which may need to be changed to first person as in the previous verse.

According to thy own heart: This seems to refer to the conscious decision made by God. As stated in the comments on 1 Chr 17.2, the heart is not the seat of emotions for Hebrew-speaking people, but rather of the intellect and will. This phrase may be rendered “according to your own will” or “because you wanted to do so.”

Thou has wrought all this greatness, in making known all these great things is literally “you have done all this greatness to make known all the greatnesses.” Moffatt says “thou hast acted in revealing all this great future,” and Revised English Bible has “you have done this great thing and revealed all the great things to come.” With basically the same meaning, Good News Translation takes all these great things to refer to David’s “future greatness.” But others think it refers to the great deeds of God himself. Parole de Vie, for example, renders the last clause as “in order to make known how great you are.” Either way the referent is basically the same: the great deeds that God does on half of David. The Septuagint does not have this final clause, and some scholars think that a scribe mistakenly added these words to the Hebrew by repeating the preceding words. Following the Septuagint, New American Bible omits in making known all these great things. Critique Textuelle de l’Ancien Testament recommends keeping this clause by giving an {A} rating to the Masoretic Text.

Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on 1-2 Chronicles, Volume 1. (UBS Helps for Translators). Miami: UBS, 2014. For this and other handbooks for translators see here .