Praise be to Allah.
It is well-known among the scholars that the keeper of Paradise among the angels is called Ridwaan, but this name is not mentioned in the Holy Qur’an or in the saheeh sunnah. Rather it is mentioned in some da‘eef (weak) reports.
Ibn al-Qayyim (may Allah have mercy on him) said: Allah, may He be glorified and exalted, called the foremost among these keepers Ridwaan, which is a name derived from the word rida (pleasure); and He called the keeper of Hell Maalik, which is a name derived from the word mulk, which refers to power and strength.
End quote from Haadi al-Arwaah (1/76).
An-Minnaawi said: The one who is appointed to guard or keep Paradise is called khaazin (translated above as keeper) because Paradise is a place that Allah, may He be exalted, has prepared to keep His slaves in. … The apparent meaning would suggest that there is only one keeper, but this is not what is meant, based on a report narrated by Abu Hurayrah: “Whoever spends two types of wealth in Allah’s cause, the keepers of Paradise, the keepers of each gate, will call him, saying ‘Come in.’” This and other hadiths clearly indicate that there is more than one keeper, but Ridwaan is the greatest of them and foremost among them. As for the greatest Messengers, they will be received by the greatest of its keepers.
End quote from Fayd al-Qadeer (1/50).
Al-Haafiz Ibn Katheer (may Allah have mercy on him) said concerning the angels:
Among them are some who are appointed in charge of Paradise and of preparing the honours for its people, preparing welcoming gifts for its inhabitants, such as garments, jewellery, dwellings, food, drink and other things such as no eye has seen, no ear has heard, nor has it crossed the mind of any human. The keeper of Paradise is an angel called Ridwaan, who is clearly mentioned in some hadiths.
End quote from al-Bidaayah wa’n-Nihaayah (1/53).
What is proven in the saheeh hadiths is that his title is Khaazin (Keeper), and his name is not mentioned. It is proven in the hadith about intercession that the Prophet (blessings and peace of Allah be upon him) said: “I will come to the gate of Paradise on the Day of Resurrection and will ask for it to be opened. The keeper will say: ‘Who are you?’ I will say, ‘Muhammad.’ He will say: ‘I was commanded not to open it for anyone before you.” Narrated by Muslim (197).
But the fact that this name (Ridwaan) is narrated in some da‘eef hadiths, in addition to the fact that it is well-known among the scholars, makes it acceptable to use this name to refer to the keeper of Paradise, in sha Allah.
It says in Fataawa al-Lajnah ad-Daa’imah (28/353):
Is Ridwaan the keeper of Paradise, and where is his name mentioned?
Answer: What is well-known among the scholars is that the name of the keeper of Paradise is Ridwaan; he is mentioned in some hadiths the soundness of which is the matter of a difference of scholarly opinion. And Allah knows best. End quote.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:
With regard to Ridwaan, he is appointed in charge of Paradise. This name of his is not proven as soundly and clearly as the name of Maalik [i.e., the keeper of Hell], but he is well-known among the scholars by this name.
End quote from Majmoo‘ Fataawa al-‘Uthaymeen (3/119).
And Allah knows best.