All the praise and glory belongs to Allah swt who is the Sustainer and Cherisher of the worlds.
The closest meaning of the word ‘Rab’ is sustainer and cherisher. Allah swt is ‘Rab’ in the global sense. He is the ‘Rab’ of every living and non-living particle of any size that exists in this whole universe. All the sovereignty of heaven and earth belongs only to Him.
Allah swt at various places in the Holy Quran invites, dictates and warns the people of all religions and races to love, respect and to be compassionate with the Parents. He educates the mankind a special sense of dignity, honor and respect to be given to the parents. Undoubtedly He is the ultimate authority and the cherisher but in order to show the importance of the parents He goes on to say in Sura-e-Kahf (17:24) "Qul rabbir ham huma kama rabbayani saghira..." which means He instructs the mankind to pray for them by calling ‘O my Lord! Have mercy on them (my parents) as they cherished me when I was little’. Here He wants the mankind to understand the magnitude of dignity, honour and respect that parents deserve by calling them as a cherisher even after the fact that He being the ultimate cherisher. He elevated their position to a very high degree by explaining to mankind that the parents share what I do in terms of sustaining and cherishing the children when they are little. Although the word ‘Rab’ used here is in a specific sense and to show the high degree of importance of the parents to the mankind, He is actually commanding mankind to honor and respect their parents exactly in the same manner as one would honor and respect Allah swt himself. This obedience is only in terms of honor & respect and not in terms of prostration and prayers (ibadat). The prayer (ibadat) is only done specific to Allah swt.
There are many places in Holy Quran & traditions of Masoomeen (a.s.) that addresses the issue of special honor and respect to be given to the parents and they...