Wages must be paid to an employee, and paid on time:
לֹֽא־תַעֲשֹׁ֥ק אֶת־רֵֽעֲךָ֖ וְלֹ֣א תִגְזֹ֑ל לֹֽא־תָלִ֞ין פְּעֻלַּ֥ת שָׂכִ֛יר אִתְּךָ֖ עַד־בֹּֽקֶר׃
You shall not defraud your fellow. You shall not commit robbery. The wages of a laborer shall not remain with you until morning.
לֹא־תַעֲשֹׁ֥ק שָׂכִ֖יר עָנִ֣י וְאֶבְי֑וֹן מֵאַחֶ֕יךָ א֧וֹ מִגֵּרְךָ֛ אֲשֶׁ֥ר בְּאַרְצְךָ֖ בִּשְׁעָרֶֽיךָ׃ בְּיוֹמוֹ֩ תִתֵּ֨ן שְׂכָר֜וֹ וְֽלֹא־תָב֧וֹא עָלָ֣יו הַשֶּׁ֗מֶשׁ כִּ֤י עָנִי֙ ה֔וּא וְאֵלָ֕יו ה֥וּא נֹשֵׂ֖א אֶת־נַפְשׁ֑וֹ וְלֹֽא־יִקְרָ֤א עָלֶ֙יךָ֙ אֶל־יְהוָ֔ה וְהָיָ֥ה בְךָ֖ חֵֽטְא׃
You shall not abuse a needy and destitute laborer, whether a fellow countryman or a stranger in one of the communities of your land. You must pay him his wages on the same day, before the sun sets, for he is needy and urgently depends on it; else he will cry to the LORD against you and you will incur guilt.
For rabbinic rulings on this topic, see Mishnah Bava Metzia 9:11-12 and the ensuing discussion in the gemara, starting at 110b and running through to the end of 112a.
These rulings are codified by Rambam in Hilchot Sechirut 11:1-5, as well as by R. Yosef Karo in Shulchan Aruch Choshen Mishpat 339.
Money owed to a businessperson according to a valid contract is a debt. Debts must also be paid and paid on time.
Ketubot 86a quotes an opinion that paying a creditor is a mitzvah. (Rashi explains that it is derived from a derashah on Vayikra 19:36 which mandates that we keep our word; Ritva provides an alternative source - Devarim 24:11 which mandates that a borrower produces a security to pay off a loan.)