History. From their earliest beginnings in 17th century, Quakers have valued and supported travel by individual Friends "under a religious concern". In most cases such Friends have traveled among settled (i.e. already established) Friends Meetings either in their immediate vicinity or at a great distance. At times, however, Friends have felt led to travel among non-Friends with a particular leading. A striking example is when Mary Fisher felt led in 1658 to travel to Istanbul to meet with Sultan Mehmed IV of the Ottoman Empire. All early Quaker leaders, especially those identified informally as the "Valiant Sixty", carried out such travels in the gospel ministry. Later Quaker journals are filled with accounts of such religious travel.
Shared discernment and support from the faith community. Friends developed very early a process for group testing, usually by one's local congregation, of such leadings. This process is now usually referred to as a "clearness committee" for one-time calls to travel and a "support committee" for the nurture and holding accountable of those led to carry out such work on a more ongoing basis. This provcess is one important example of what Friends refer to as "eldership" or eldering. The process of shared discernment of God's call and holding an individual accountable for carrying out that call faithfully is the same whether or not it is carried out by persons formally recognized as elders or by others not so designated.
It is considered important that Friends undertaking such work obtain a written minute of religious concern often referred to as a "traveling minute" that describes the faith community's official endorsement of the individual's calling to a particular or more ongoing religious work among Friends or in the wider world. In cases of distant travel among Friends, these minutes are also often endorsed by the Friend's yearly meeting (regional association).
It is considered critical that Friends undertaking this type of work travel with a spiritual companion or "elder". The elder both provides prayerful support to the "minister" (both during any programs the minister is leading and before and after) and also to hold the minister accountable for faithful exercise of her or his call.
There is separate webpage with more information on Eldering
Biblical underpinnings. Early Friends saw themselves as continuing a pattern of religious work described in Bible, especially the New Testament. The importance of traveling with an elder ties in with the fact that Jesus sent out his followers in pairs. See Mark 9-13. The resurrected Jesus gave similar briefer instructions in Matthew 28-18-20. Many examples can also be found in the Book of Acts and Paul's letters. You can read many reports of the process of discerning in prayer with others what particular travel or religious task Paul and others were called to carry out.
Engaging with a Monthly Meeting about Ministry describes one Friend's request to her meeting for a minute of travel and how the meeting responded.
For a description of some of the types of work that Anne Patterson & I (Peter Blood) have done see Our Travel under Concern.