Vetaher Libeinu

Vetaher libeinu leavdecha b'emet.

And purify our hearts to serve Hashem truthfully.

From the liturgy, for example, from the blessing in the Shabbat Amidah that ends in "mekadesh hashabbat" - "he who sanctifies the Sabbath."
Video below from the album "Chassidic and Shabbat Songs"