How sound are these two narrations, in terms of their chain of transmission and text?

The statement that supplications are answered at the graves of prophets and righteous individuals has no basis in Islamic law (Sharia). None of the Companions, their Successors, or the followed Imams ever uttered such a thing; rather, they explicitly stated the opposite. The innovated practices at graves range from asking the deceased for help or seeking their intercession, or asking Allah through them (which is an innovation by consensus of Muslims), or the belief that supplication at a grave is answered, which is among the reprehensible, innovated, and forbidden acts. For acts of worship are only established by the Qur'an, the Sunnah, and the path of the early predecessors.