Rebbe Nachman ztk’l speaks of the importance of joining Tehillim with teshuva. There is a well-known kabbalistic teaching of the fifty gates of return of which forty-nine we have full access to. However, the fiftieth gate is personally governed by Hashem and is accessible only through special permission. The forty-nine gates parallel to the forty-nine letters in the Hebrew names of the twelve tribes.
The Jewish people are granted special privilege to the forty-nine gates of return by virtue of their inner awakening to return to Hashem; however many cannot attain this level on their own. Recitation of Tehillim awakens the G-dly soul making us worthy of return and enabling access to these main gates.
Tehillim grants access to the letter of the tribes attached to each of these gates thus allowing us to truly return to Hashem. Dovid HaMelech is called the ‘Sweet Singer of Israel’ because the words of Tehillim have the power to awaken teshuva through Divine inspiration.
It was specifically in Mitzrayim where the tribes passed through the forty-nine gates of teshuva that made them worthy of the exodus and redemption.