One riding behind another: is he liable?

Khilas reported that Sayyiduna Ali (may Allah be pleased with him) held liable both of those riding together on one mount.

Al-Sha'bi said that Shurayh said: There is no liability on the one sitting behind the rider.

Al-Shaybani said that al-Sha'bi said regarding the one sitting behind the rider: The two of them shall be partners.

Ash'ath said that al-Hasan al-Basri said: The rider and the one seated behind him are equal; whatever the mount has trampled, and whatever liability arises, shall be between the two of them, half and half.

Abu al-Ala said that Qatadah and Abu Hashim both said: The one seated behind the rider shall be liable to the same extent as the one seated in front.

Al-Shaybani said that al-Sha'bi said: The one seated behind the rider shall also be held liable.