אֶֽת־הַדָּבָ֞ר אֲשֶׁר־כָּרַ֤תִּי אִתְּכֶם֙ בְּצֵאתְכֶ֣ם מִמִּצְרַ֔יִם וְרוּחִ֖י עֹמֶ֣דֶת בְּתוֹכְכֶ֑ם אַל־תִּירָֽאוּ׃ (ס)
The word that I covenanted with you when ye came out of Egypt have I established, and My spirit abideth among you; fear ye not.
Read Jewish philosophy on Haggai 2:5: Rambam's Guide for the Perplexed, Saadia Gaon, and classical Jewish philosophical sources, free online.