Genesis 20:17

So Abraham prayed unto God: and God healed Abimelech, and his wife, and his maidservants; and they bare children.

So Abraham prayed unto God. Although the efficacy of prayer is not expressly mentioned until the Gospel age (Matthew 7:7; James 5:14-15), there are numerous remarkable instances of its power and influence recorded throughout the Old Testament History. The agency of Abraham being employed in intercessory prayer for the sick, the divine favour to him was manifested anew by an immediate answer in the restoration of Abimelech and his household; and the notice of the fact would tend to raise the patriarch in the estimation of the Gerar people, who would feel themselves laid under obligations for so important a service.

And his maid-servants, [Hebrew, wª'amhotaayw (H519)] - and his female slaves, who were concubines.

And they bare. What was the partitular form of punishment inflicted on the inmates of Gerar palace has been a subject of discussion. It could not be sterility in the women; because the announcment of Sarah's promised son in the following spring was made at Hebron the day previous to the destruction of Sodom; and supposing the patriarch to have left Hebron immediately thereafter, and all transactions at Gerar had taken place before the birth of Isaac, how could the alleged barrenness of Abimelech's wives have been ascertained within so brief a space of time. Hence, some have concluded that this chapter does not stand in its proper place, and that its details refer to a sojourn in Gerar previous to the events related in the chapters immediately preceding. Besides, it is evident that the judgment of God fell particularly upon Abimelech Himself. But, as Calvin ('Comment. in Genesin') remarks, this matter does not form an article of faith, and therefore it may be left undecided. The circumstances at Gerar differed widely from what took place at the Egyptian court, since Abimelech acted in the innocency of his heart, and his people were comparatively a righteous nation; he was therefore dealt with more leniently than the Egyptians.