וַיִּתֵּ֬ן בְּפִ֨י ׀ שִׁ֥יר חָדָשׁ֮ תְּהִלָּ֪ה לֵֽאלֹ֫הֵ֥ינוּ יִרְא֣וּ רַבִּ֣ים וְיִירָ֑אוּ וְ֝יִבְטְח֗וּ בַּיהוָֽה׃
And He hath put a new song in my mouth, even praise unto our God; many shall see, and fear, and shall trust in the LORD.
Read kabbalistic (mystical) interpretation of Psalms 40:4: and classical mystical sources.