Is there any idiom or proverb that means "the evidence contradicts what you claim"?
There is a proverb in Persian that says:
"Should/ shall we believe the rooster's tail or the fox's oaths to God?!"
Its etymology is like this:
Once a fox who was passing a village, stole a rooster/cock and put it into his backpack, and ran away. But a villager saw him and informed everybody, so some villagers ran after him and finally got him in a corner. The villagers asked him to give back the rooster to them, but the fox repeatedly was saying:
"I swear to God that I have no rooster with me, I don't know what you are talking about", but he didn't know that tail of the rooster was sticking out his backpack.
So the people replied to him sarcastically and mockingly:
"Should/ shall we believe that rooster's tail or your oaths to God?"
It implies that "the evidence contradicts what you claim" ( i.e., we know that you are lying!) or " your actions contradict your words".
A famous merchant claims that his business is not doing well, for avoiding paying his taxes, but lives in a mansion and has many other luxurious items under his name. So the officials would say him:
"Mr.___! Should (or shall) we believe the rooster's tail or the fox's oaths? [ Should we believe what you claim (=not having good income) or what we have as evidence (=list of your properties) ?!] Unfortunately, all the evidence contradict what you claim and you should pay your taxes!!"
Is there any idiom or proverb in English that would convey the same connotation?
This proverb is used among politicians a lot! For example; you can see that its connotation is shown in the following picture. This man is a former president and has stated something about parliamentary elections, but one of his opponents has put this picture in his blog trying to say "the evidence contradicts what you said".