We often get requests from parishes for short prayers to incorporate at the end of the Prayers of the Faithful, and we think this is a good practice. Listed below is an example of a stewardship prayer you could use as-is or adjust as you see fit for your own parish.
Lord, hear our prayer as we seek to be good stewards of the many gifts you have given to us. Give us wisdom to discern Your will for us, strength to meet the challenge, and the grace to remain committed to You. Help us to use our Time, Talent, and Treasure for Your greater honor and glory. In your name we pray. Amen.