(a) This same hadith is reported from Wathilah bin al-Asqa' (may Allah be pleased with him) through another chain, and its chain too is sahih (authentic).
(b) In the above hadith, Wathilah's (may Allah be pleased with him) being of the family is particular to him; establishing it for the whole Ummah is far-fetched. And calling Wathilah (may Allah be pleased with him) family is also by way of resemblance, not in the true sense.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2871