Here, Allah is teaching us to pray to reach success in our affairs. He is also alerting us to seek success from His Self (‘Ind’; the forces that are revealed through dimensional emergence to consciousness from the Names of Allah that comprise one’s essence)… Thus, whenever we are praying for something regarding His essential qualities, such as Knowledge, Rahmah and Power, we should ask from His ‘Ind’.
رَبِّ لَا تَذَرْنِي فَرْدًا وَأَنْتَ خَيْرُ الْوَارِثِينَ
Rabbi la tadharnee fardan wa anta khayru l-waaritheena
My Rabb... Do not leave me on my own in life (grant me an heir)! You are the best of heirs.
Zachariah (as) had grown old, but still did not have any children… So he prayed to his Rabb with the verse above and his prayer was accepted; he was bestowed with a son whom he called John.
This was the John who gave the good news of the coming of Jesus (as)…
Those who want to have children should recite this verse. The most effective way to do so is by performing the salat called ‘Hajat’ after midnight, and then repeating this prayer 1,000 times for a number of successive nights.
 Quran 21:89.