Praise be to Allah.
Muslim (384) narrated from ‘Abdullah ibn ‘Amr ibn al-‘Aas that he heard the Prophet (blessings and peace of Allah be upon him) say: “When you hear the muezzin, say what he says, then send blessings upon me, for whoever sends blessings upon me, Allah will send blessings upon him tenfold. Then ask Allah to grant me al-waseelah, for it is a station in Paradise which only one of the slaves of Allah will attain, and I hope that I will be the one. Whoever asks for al-waseelah for me, intercession will be permissible for him.”
It was narrated by Imam Ahmad in al-Musnad (8770), Ibn Abi Shaybah in al-Musannaf (31784), al-Jahdami in Fadl as-Salaah (46), Abu Ya ‘la in his Musnad (6414), and Ibn Raahawayh in his Musnad (297), via :Layth, from Ka‘b, from Abu Hurayrah, that the Prophet (blessings and peace of Allah be upon him) said: “Send blessings upon me, for that is a means of purification for you. And ask Allah to grant me al-waseelah, for it is a status in the highest part of Paradise, which no one will attain except one man, and I hope that I will be him.”
This is a da‘eef isnaad; Layth is ibn Abi Sulaym, who is da‘eef and confused when narrating hadith. He was classed as da‘eef by Ahmad, Ibn Ma‘een, an-Nasaa’i, Ibn Hibban and others.
See: Mizaan al-I‘tidaal (3/420)
Ibn Katheer said in his Tafseer (6/413):
Its isnaad includes some narrators who were cricised.
It was also classed as da‘eef by al-Albaani in Tahqeeq Fadl as-Salaah li’l-Jahdami, and by the commentators on al-Musnad.
The meaning of the hadith is sound in general terms, but this version is da‘eef in its isnaad.
And Allah knows best.