Hadithcore
Musnad Ahmad 3942
graded· 1296

It was narrated from 'Abdur-Rahman bin Yazeed that

'Abdullah bin Mas'ood went to the bottom of the valley and stood perpendicular to the Jamarat. putting the mountain behind his back, then he stoned (the Jamarat) and he said. This is the place where the one to whom Sooratal-Baqarah was revealed stood.

References1 variant
Arabic/English book
Book 26, Hadith 3942