וְשִׁבְעָ֣ה הַכֹּהֲנִ֡ים נֹשְׂאִים֩ שִׁבְעָ֨ה שׁוֹפְר֜וֹת הַיֹּבְלִ֗ים לִפְנֵי֙ אֲר֣וֹן יְהוָ֔ה הֹלְכִ֣ים הָל֔וֹךְ וְתָקְע֖וּ בַּשּׁוֹפָר֑וֹת וְהֶחָלוּץ֙ הֹלֵ֣ךְ לִפְנֵיהֶ֔ם וְהַֽמְאַסֵּ֗ף הֹלֵךְ֙ אַֽחֲרֵי֙ אֲר֣וֹן יְהוָ֔ה הולך [הָל֖וֹךְ] וְתָק֥וֹעַ בַּשּׁוֹפָרֽוֹת׃
And the seven priests bearing the seven rams’horns before the ark of the LORD went on continually, and blew with the horns; and the armed men went before them; and the rearward came after the ark of the LORD, [the priests] blowing with the horns continually.
Shenei Luchot HaBerit
This is also why Moses in his blessing of the tribe of Gad in Deut. 33,21 refers to that tribe as having performed צדקת ה' עשה ומשפטיו עם ישראל, "both a deed of righteousness vis-a-vis G–d and one of justice did he (the tribe) perform with Israel." From a legal point of view the tribe of Gad did only have to take part in the conquest of the land, something which took seven years. The additional seven years that were required to parcel out the land was an act of צדקה, something volunteered. By honoring this voluntary undertaking, the tribe qualified for Moses' unstinting praise. The Torah wishes us to apply such modes of behavior not only when it concerns utterances that may be financially costly for us, but also when such utterances imply undertakings by our souls, i.e. our religious conduct.