من لا يحضره الفقيه, volume 2, page 475

Hadith.3000 - Mu'awiya ibn Ammar narrated from Abu Abdullah (as): Regarding a man who took 21 pebbles for stoning (Rami) and threw them, realizing afterward that he had one extra but could not determine which station he had missed: "He should return and throw one pebble at each station. If a pebble falls from someone's hand and they do not know which one it is, they should take one from under their feet and throw it." Imam (as) also said: "If you throw a pebble and it lands in a litter (carrying device), you should replace it with another. However, if it hits a person or an animal and then lands on the target (the pile of pebbles), it is sufficient." Regarding someone who threw only four pebbles at the first station but threw seven at the second and third: "He should return and throw three more at the first station, and the rest is complete. If he threw only three at the second station and completed the third, he should return and throw seven at the second. If he threw four at the second station, he must return and throw three more." When asked about someone who performs the stoning in reverse order, Imam (as) replied: "He must redo the stoning for the middle station and the Jamrat al-Aqaba in order."

Translation: Bab Ul Qaim Publications — attributed by Thaqalayn·The Arabic above is the original.