וַיֹּ֤אמֶר הַמֶּ֙לֶךְ֙ אֶל־עֲמָשָׂ֔א הַזְעֶק־לִ֥י אֶת־אִישׁ־יְהוּדָ֖ה שְׁלֹ֣שֶׁת יָמִ֑ים וְאַתָּ֖ה פֹּ֥ה עֲמֹֽד׃
Then said the king to Amasa: ‘Call me the men of Judah together within three days, and be thou here present.’
Rashi on II Samuel
Rally the men of Yehudah. That they should be here within three days.
Rashi on II Samuel
And then you be back here [to meet me]. After three days be sure to be back here before me because he [Dovid] wanted to chase after Shevah, the son of Bichri.