It is vital that Friends hoping to travel in the ministry test their concern thoroughly; we may be reminded of the practice of John Woolman, who travelled in the ministry extensively:

Having been some time under a religious concern to prepare for crossing the seas in order to visit Friends in the northern parts of England, and more particularly in Yorkshire, after weighty consideration I thought it expedient to inform Friends at our monthly meeting at Burlington of it, who, having unity with me therein, gave me a certificate. And I afterwards communicated the same to our quarterly meeting, and they likewise certified their concurrence. Some time after, at the General Spring Meeting of Ministers and Elders, I thought it my duty to acquaint them with the religious exercise which attended my mind, with which they likewise signified their unity by a certificate, dated the 24th of third month, 1772, directed to Friends in Great Britain.