From Martin Luther’s, “A Sermon on the Estate of Marriage” [Luther’s Works (Fortress Press), 44:12]:

But this at least all married people should know. They can do no better work and do nothing more valuable either for God, for Christendom, for all the world, for themselves, and for their children than to bring up their children well. In comparison with this one work, that married people should bring up their children properly, there is nothing at all in pilgrimages to Rome, Jerusalem, or Compostella [the home of a famous shrine in Spain], nothing at all in building churches, endowing masses, or whatever good works could be named. For bringing up their children properly is their shortest road to heaven. In fact, heaven itself could not be made nearer or achieved more easily than by doing this work. It is also their appointed work. Where parents are not conscientious about this, it is as if everything were the wrong way around, like fire that will not burn or water that is not wet.