Riyad as-Salihin (The Meadows of the Righteous)
by Imam Nawawi
30. Chapter: Intercession
Allah Almighty says, "Those who join forces for good will receive a reward for it." (W4:84; H4:85)
246. Abu Musa al-Ash'ari said, "When someone with a need came to the Prophet, may Allah bless him and grant him peace, he turned to those sitting with him and said, 'Intercede on behalf of others and you will get the reward. Allah achieves what He likes on the tongue of His Prophet.'" [Agreed upon]
One variant has "what He will"
247. Ibn 'Abbas said in the story of Barira and her husband, "The Prophet, may Allah bless him and grant him peace, asked her, 'Will you take him back?' She said, 'Do you command me to, Messenger of Allah?' He replied, 'I am interceding.' She said, 'I have no need of him.'" [al-Bukhari]