Abu Hamza Thumali has narrated that one day ‘Abdullah bin Umar approached Imam Zayn al-‘abidin and said, “You say that “My grandfather ‘Ali ’s Wilayah was presented to Yunus but he was reluctant so Allah dropped him in the belly of a fish.” Imam said, No doubt. I did say so. May your mother sit in mourning for you.” ‘Abdullah said, “If what you say is true, then show me some sign supporting it.” (Abu Hamza says:) Imam put a band on his (‘Abdullah’s) and my eyes and after a few moments asked us to open the bands. When we untied the bands what we had a vision was that we were on seashore. Its waves were rising high. ‘Abdullah bin Umar said, “O my leader! My blood (responsibility of my death) will be upon you.” Yunus said, “Do not become restless. I want to show you the sign of my truthfulness.” Then he called upon the fish.
A giant fish like a big mountain raised its head out of water saying: “Labbaik, O Wali of Allah!” Imam asked it: “Who are you?” It replied, “I am the fish of Yunus.” Imam said, “Narrate the story of Yunus to us.” It said, O my leader! Right from Adam up to your grandfather Muhammad Allah had not appointed any Prophet to whom the Wilayah of you, Ahl al-Bayt was not presented. The one who accepted it remained protected and the one who denied it was involved in trouble until Allah sent Yunus with His Message and asked him through revelation to accept the Wilayah of Amir al-Mu’minin ‘Ali and thereafter of the rightly-guided Imams born of ‘Ali ’s lineage along with other matters revealed to him. Yunus said, How can I accept the Wilayah of those whom I have not yet seen nor know! Then he came to the shore of the sea. Allah revealed to me to swallow him but without damaging his bones. Yunus remained in my belly for forty days. I ferried him in rivers and oceans and darkness and he was crying: laa illaah anta subhaanaka innee kuntu minaz zscholareen (and continued to pray to Allah Almighty) that I have accepted the Wilayah of Amir al-Mu’minin and of the rightly guided Imams from his progeny. When he put faith on the Wilayah of you gentlemen, Allah ordered me to throw Yunus out so I disgorged him on the shore. Hearing this Imam said, “O fish! Go back to your abode.” So it went away. The waves settled down and the water became calm.
Reference: Hayat Al-Qulub, Vol. 1, Stories of the Prophets