Luke 14:28-31

For which of you, desiring to build a tower, doth not first sit down and count the cost, whether he have wherewith to complete it? Lest haply, when he hath laid a foundation, and is not able to finish, all that behold begin to mock him, saying, This man began to build, and was not able to finish. Or what king, as he goeth to encounter another king in war, will not sit down first and take counsel whether he is able with ten thousand to meet him that cometh against him with twenty thousand?