Since Mattathias’ speech just ended, translators should start a new paragraph here.

When he had finished speaking these words may be rendered “When Mattathias had finished speaking.”

A Jew came forward in the sight of all may be expressed as “another Jewish man stepped forward while everyone was watching.”

To offer sacrifice upon the altar in Modein: It will be helpful to make it clear that this was a sacrifice offered on pagan altar. (The only Jewish altar in Judea at that time was at the Temple in Jerusalem.) So we may express this clause as “He planned to offer a sacrifice to a foreign god there on the altar in the town of Modein.”

According to the king’s command may be rendered “as the king had commanded.”

The translator’s problem in this verse is to convey quite a bit of information in a way that can be followed easily. Good News Bible succeeds in this, even though it is long. Another possible model is:

• When Mattathias finished speaking, another of the Jewish men stepped forward while everyone was watching, and prepared to do what the king had commanded. He was going to offer a sacrifice [to a pagan/another god] there on the altar in Modein.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Maccabees. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here.