This wiki answer contains, those quotes, which are straightforward not related to Gita.
Whatever has happened has happened for the good. What is happening is also happening for the good. Whatever will happen will be for good also.
What did you lose that you cry about? What did you bring with you, which you think you have lost? What did you produce, which you think got destroyed? You did not bring anything, whatever you have, you received from here. Whatever you have given, you have given only here. Whatever you took, you took from God. Whatever you gave, you gave to Him. You came empty handed, you will leave empty handed.
The world isn't bad because of bad people's deed. It's bad because inaction of good people.
There was in fact a similar/inspired dialogue in a Hindi movie Singh Saab the Great. See this video.
In gita Krishna explicitly literally said that: "anyone believing in him should believe that Bhagwad Gita is Lord Krishna Himself"