When he returned and reached the door, he found it slightly ajar

والصَّلَاةُ والسَّلاَمُ عَلَى سَيّدِنَا مُحَمَّدٍ أَشْرَفِ اْلمُرْسَلِيْنَ وَعَلَى آلِهِ وَصَحْبِهِ الطَّيّبِيْنَ الطَّاهِرِيْن

Muslim in his Sahih, ‘Ahmad in his Musnad, and Al-Hakim in his Mustadrak related from ‘Abu Hurayrah, may Allah accept his deeds, that he said: "I used to call my mother to Islam as she was still a polytheist.

One day, I invited her, but she spoke of the Messenger of Allah ﷺ in a manner I disliked [alluding to her speaking ill of the Messenger of Allah ﷺ, and we seek refuge in Allah from such].

I went to the Messenger of Allah ﷺ in tears and said: 'O Messenger of Allah, I have been calling my mother to Islam, yet she refuses to accept my words. Today, I invited her again, and she said about you something I found deeply upsetting. Please supplicate to Allah to guide the mother of ‘Abu Hurayrah.' The Messenger of Allah ﷺ then supplicated: ‘O Allah, guide the mother of ‘Abu Hurayrah.’"

‘Abu Hurayrah continued:  "I left, overjoyed with the supplication of the Prophet of Allah ﷺ. When I returned and reached the door, I found it slightly ajar. My mother heard the sound of my footsteps and said, 'Stay where you are, O ‘Abu Hurayrah!'. I then heard the splashing of water. She had bathed, donned her dir^ [a robe resembling an abaya], and, in her haste, left without properly covering her head. She opened the door and said:  'O ‘Abu Hurayrah, I testify that there is no Deity but Allah, and I testify that Muhammad is His servant and Messenger.'" 

‘Abu Hurayrah concluded: "I returned to the Messenger of Allah ﷺ, weeping with joy! I said: 'O Messenger of Allah, rejoice, for Allah has answered your supplication and guided the mother of ‘Abu Hurayrah!' He praised Allah, extolled Him, and spoke words of goodness.

I then said: 'O Messenger of Allah, supplicate to Allah that He makes both me and my mother beloved to His believing servants, and that He makes them beloved to us!' The Messenger of Allah ﷺ then said: 'O Allah, make Your servant – meaning ‘Abu Hurayrah – and his mother beloved to Your believing servants, and make the believers beloved to them.' There is no believer who hears of me or sees me except that he loves me."