"Power whereby"

1. 1 Ne. 5: 8
   8 And she spake, saying: Now I know of a surety that the Lord hath commanded my husband to flee into the wilderness; yea, and I also know of a surety that the Lord hath protected my sons, and delivered them out of the hands of Laban, and given them power whereby they could accomplish the thing which the Lord hath commanded them. And after this manner of language did she speak.
2. Hel. 8: 12
   12 And now behold, if God gave unto this man such power, then why should ye dispute among yourselves, and say that he hath given unto me no power whereby I may know concerning the judgments that shall come upon you except ye repent?