The power and efficacy of the prayers of the people of God, when rightly offered to him; and the obligation and encouragement thence arising to be much in prayer : A sermon preach'd at Mansfield, Aug. 4. 1741. At a time set apart for prayer for the revival of religion; and on the behalf of Mrs. Eunice, the daughter of the Reverend Mr. John Williams, (formerly pastor of Deerfield) who was then on a visit there, from Canada; where she has been in a long captivity. /