Jami` at-Tirmidhi Book 27, Hadith 14
the Prophet said: "Merely maintaining the ties of kinship is not adequate. But connecting the ties of kinship is when his ties to the womb are severed and he connects it."
" Abu Al-Laithi complained(of an illness). So 'Abdur-Rahman bin 'Awf visited him. He said: 'The best of you, and the most apt to maintain good relations, as far as I know, is Abu Muhammad('Abdur-Rahman bin 'Awf). So 'Abdur-Rahman bin 'Awf' said: 'I heard the Messenger of Allah saying : "Allah, Most Blessed and Most High, said: 'I am Allah, and I am Ar-Rahman. I created the Rahim(womb), and named it after My Name. So whoever keeps good relations with it, I keep good relation with him, and whoever severs it, I am finished with him.'"
the Messenger of Allah said: "The one who severs ties will not enter Paradise." Ibn Abi 'Umar said: "Sufyan said: 'Meaning: Ties of the womb."