What is the ruling on supplication during prostration (sujud) and bowing (ruku), and is it obligatory or a Sunnah, and does the prayer become invalid by omitting it, and is it permissible to supplicate for personal matters?

Supplicating during rukūʿ (bowing) is mustaḥabb (recommended), as it was reported that the Prophet, peace and blessings be upon him, used to say in his bowing: "Glorified be You, O Allah, our Lord, and with Your praise, O Allah, forgive me." Some scholars considered it makrūh (disliked), arguing that rukūʿ is for glorification, but the correct view is that it is permissible.

As for supplicating during sujūd (prostration), it is mustaḥabb (recommended) with strong emphasis, due to the Prophet's, peace and blessings be upon him, saying: "The closest a servant is to his Lord is while he is prostrating, so increase your supplication [therein]," and due to his, peace and blessings be upon him, actions, as he used to make various supplications during his prostration. It is permissible for the worshipper to supplicate during his prostration for anything he wishes, concerning matters of this world and the hereafter, and the prayer is not invalidated thereby. However, the Imam should not prolong the prayer for the congregants by excessive supplication.