Reference for Numbers 7:3

וַיָּבִ֨יאוּ אֶת־קָרְבָּנָ֜ם לִפְנֵ֣י יְהוָ֗ה שֵׁשׁ־עֶגְלֹ֥ת צָב֙ וּשְׁנֵ֣י עָשָׂ֣ר בָּקָ֔ר עֲגָלָ֛ה עַל־שְׁנֵ֥י הַנְּשִׂאִ֖ים וְשׁ֣וֹר לְאֶחָ֑ד וַיַּקְרִ֥יבוּ אוֹתָ֖ם לִפְנֵ֥י הַמִּשְׁכָּֽן׃

And they brought their offering before the LORD, six covered wagons, and twelve oxen: a wagon for every two of the princes, and for each one an ox; and they presented them before the tabernacle.