Sunan al-Tirmidhi #2004

لَيْسَ الْوَاصِلُ بِالْمُكَافِئِ وَلَكِنِ الْوَاصِلُ الَّذِي إِذَا قُطِعَتْ رَحِمُهُ وَصَلَهَا

The Messenger of Allah (ﷺ) said: 'The one who maintains ties of kinship is not the one who reciprocates. Rather, the one who maintains ties of kinship is the one who, when his relatives cut him off, maintains his ties.'