Hi Ameer,
I too carried cash physically with me and declared it at the point of entry at Canada. No questions or verification done. But, on our return via London, we had to deal with the customs authorities in-transit as we were bringing back the same cash with us. They asked us to prove the source of funds and any receipts. Luckily, I was carrying original receipts from UAE Exchange. They say that if they search our bags and find more cash than we inform them or if they are not satisfied with the proofs, they will confiscate our cash and we can challenge it in London Court. So, better carry proofs.
Bonjour Canada