Sayyiduna Fadalah bin Ubayd (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "I am a guarantor, and the guarantor is the one who takes responsibility, for the one who believes in me, accepts Islam and strives in the path of Allah: for him are the glad tidings of a house in the outer part of Paradise and a house in the middle of Paradise. And I am a guarantor for the one who believes in me, accepts Islam and emigrates: for him are the glad tidings of a house in the outer part of Paradise, a house in the middle of Paradise and a house in the highest chambers of Paradise. Whoever does that has left no pursuit of good unsought and no escape from evil untaken; he may die wherever he wishes to die."
Al-Muzani mentioned here the hadith of Abu Sa'id al-Khudri concerning guarantee, and the chain of Abu Sa'id's hadith is weak.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحوالة / 11394