How can one respond to those who insult the Companions of the Messenger of Allah, peace and blessings be upon him?

Love for the Companions of the Messenger of Allah, peace and blessings be upon him, is obligatory due to Allah's praise for them, their faith in Him, their support for His Prophet, and their striving in the way of Allah. All the Companions are considered trustworthy by the Ahl al-Sunnah wal-Jama'ah (Sunnis), and Allah has praised them in the Qur'an and Sunnah for the sacrifices they made with their wealth and lives. Allah chose them to be the ministers of His Prophet, fighting for His religion. Slandering the Companions of the Messenger of Allah, peace and blessings be upon him, is a sign of the people of innovation and heresy who seek to invalidate the Sharia by discrediting its narrators. Slandering them is an accusation against Islam and an attempt to harm the Prophet, peace and blessings be upon him.