Luke 9:62

Having put his hand to the plough, and looking back; the husbandman who puts his hands to the plough must keep them, and his eyes too, fixed upon it. If he looks back, as for example to converse with those behind him, his work will be poorly done. The Syrian plough, being light, required the weight of the ploughman's body on it to keep it in the furrow. If he looked off, it would start aside. So he who would be a worthy servant of Christ must give him his whole heart and his whole time.

Fit for the kingdom of God; fit for the ministry of Christ's gospel in his kingdom. Such was plainly the original application of these words. But they apply with equal force to every kind of service which Christ requires. No man who is not ready to leave all when Christ calls, is prepared to serve him on earth, or enjoy him in heaven.