I have heard that the prophet or president of the Mormon Church can not lead the Church astray. Do you know of any quotes on this topic? Thank you.
It seems that the original quote to which you refer may have been lost in the antiquity of the Restoration as implied by the following quote from Elder Theodore Moyle Burton made in the October 1961, General Conference Of the Mormon Church—
“A seer then is one who may see God, who may talk with God, who may receive personal instruction from God. Our prophet is a seer and a revelator. I do not know who originally taught the doctrine. I was told once that it was taught by President Heber J. Grant, but I was taught this doctrine by Elder Marion G. Romney, who told me that the Lord will never let his prophet the seer, lead his people astray. Men in all ranks on this earth and in the Church have fallen from grace, but the Lord will never permit the great prophet, our seer, and revelator, to fall or to lead the people astray. Before this could happen God must of necessity remove that man from the earth.”