Reciting منها خلقناكم when throwing sand in the grave

Q: Is there any authentic hadith from the books of hadith about: When throwing the first handful one should say, "Of this (i.e. the earth) We created you," and on the second one should say, "And to it shall We cause you to return," and on the third handful one should say, "And of it We shall cause you to be resurrected a second time. Please give me the references.

Is it kufr to say that a certain medicine cures

Q: Is it kufr to say that this medicine cures like acne as example. Like is it kufr to put your trust in that medicine? Before I read a fatwa of someone asking that question but they said its not, I don't really remember. But now I am hearing that Allah cures him not the medicine, so I am confused. So whenever I say this medicine has a cure for this, I think is the cure from Allah or Allah put the cure in the medicine. But I know if Allah wills he wouldn't let him be cured by that medicine. Did I commit kufr?