I believe he did reference Amos;
"Behold, the days come, saith the Lord GOD, that I will send a famine in the land, not a famine of bread, nor a thirst for water, but of hearing the words of the LORD: And they shall wander from sea to sea, and from the north even to the east, they shall run to and fro to seek the word of the LORD, and shall not find it" (Amos 8:11-12)
And I'll add:
"Because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it" (Matthew 7:14).
"For many walk, of whom I have told you often, and now tell you even weeping, that they are the enemies of the cross of Christ: Whose end is destruction, whose God is their belly, and whose glory is in their shame, who mind earthly things" (Philippians 3: 18-19)
"For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ" (2 Corinthians 11:13). Also Romans 16:18, 1 Timothy 6:3-21, Luke 12:16-21.
"Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition" (2 Thessalonians 2:3).