Occasional hearing is the practice of attending worship services

Service of worship

In the Protestant denominations of Christianity, a service of worship is a meeting whose primary purpose is the worship of God. The phrase is normally shortened to service. It is also commonly called a worship service...

or preaching by ministers of denominations other than one's own. Historically, this practice has been resisted and, in some cases, even matter of church discipline amongst churches that study confessional integrity. Churches which, traditionally, have resisted the practice tend to be theologically conservative and confessional.