In the days when Herod was king of Judea there was a certain priest whose name was Zachariah, of the daily service (the division) of Abia; and his wife was also a descendant of Aaron, and her name was Elizabeth.
Then the angel said to her, The Holy Spirit will come upon you, and the power of the Most High will overshadow you [like a shining cloud]; and so the holy (pure, sinless) Thing (Offspring) which shall be born of you will be called the Son of God. [Exod. 40:34; Isa. 7:14.]
Because of faith also Sarah herself received physical power to conceive a child, even when she was long past the age for it, because she considered [God] Who had given her the promise to be reliable and trustworthy and true to His word. [Gen. 17:19; 18:11-14; 21:2.]