Prayer

Key verses
Ecclesiastes 5:2 - God is in heaven and you are on earth, so let your words be few.

John 2:19 - Jesus answered them, "Destroy this temple, and I will raise it again in three days."

Ecclesiastes
Solomon's statement in 5:2 remind me of Jesus' own words when he was teaching others how to pray.  We should not babble on 'like the pagans', taking pride in our eloquence, but rather come humbly before God, knowing that he already knows and understands what you haven't completely thought out for yourself yet.  Yet another likeness to the New Testament are the phrases on vows, which are like oaths.  If we vow by God that we will do something, and then don't do it, we don't give God the honour he deserves.

Jeremiah
Jeremiah sure was a persevering individual!  He even prayed for the people of Judah even though God told him not to bother, because destruction was going to come (see 14:11).