Vetaher Libeinu

Vetaher libeinu leavdecha b'emet.

And purify our hearts to serve Hashem truthfull​y.

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"