Here is a responsorial psalm from the Jerusalem Bible version of Psalm 50 (which is Psalm 51 using the Masoretic numbering sequence), verses 3 to 4, 12 to 13, and 18 to 19:

A humbled, contrite heart, O God, you will not spurn.

Have mercy on me, God, in your kindness.

  In your compassion blot out my offence.

O wash me more and more from my guilt

  and cleanse me from my sin.

A humbled, contrite heart, O God, you will not spurn.

A pure heart create for me, O God,

  put a steadfast spirit within me.

Do not cast me away from your presence,

  nor deprive me of your holy spirit.

A humbled, contrite heart, O God, you will not spurn.

For in sacrifice you take no delight,

  burnt offering from me you would refuse,

my sacrifice, a contrite spirit.

  A humbled, contrite heart you will not spurn.

A humbled, contrite heart, O God, you will not spurn.