Adult Children Obeying their Father? Horrors!

Calvin on Jer 35:18 

Here the Prophet, that he might affect the Jews more deeply, promises a reward to the sons of Jonadab, because they obeyed their father; and he promises them a blessing from God. Nor is it to be wondered at, for this commandment, as Paul says, is the first to which a promise is annexed. (Eph_6:2) God promises generally a reward to all who keep the Law, for every command has in general connected with it the hope of reward; but this is in a special manner added to the Fifth Commandment: “Honor thy father and thy mother, that thou mayest prolong thy life,” etc. It is, then, nothing strange that God promised a reward to the Rechabites, because they followed the command of their father, for he had promised that in the Law.