Textual: Limhi cites the Lord, and gives a precise quotation. He does not reference the source of the quotation, presuming that his people knew the source. We do not have this reference in any of our scriptures. The two possible sources for “unknown” scripture are the brass plates and the large plates of Nephi (which Mormon abridged). The sentiment is stated differently in Job:
Job 4:7 Remember, I pray thee, who ever perished, being innocent? or where were the righteous cut off?
Job 4:8 Even as I have seen, they that plow iniquity, and sow wickedness, reap the same.
The righteous have access to God’s blessings upon condition of their righteousness. When they are not righteousness, they reap that unrighteousness. In Limhi’s quotation, those transgressions become a “stumbling block.” This does not necessarily mean that the Lord places obstacles in our way, but rather that our own actions reap consequences that make life more difficult for us.