Jesus HIMSELF calling Peter the Stumbling Block/Rock, directly, no assumptions, no jumps, straight and clear:

[Jesus] turned
στραφεὶς (strapheis)

[and] said
εἶπεν (eipen)

to Peter,
Πέτρῳ (Petrō)

“Get
Ὕπαγε (Hypage)

behind
ὀπίσω (opisō)

Me,
μου (mou)

Satan!
Σατανᾶ (Satana)

You are
εἶ (ei)

a stumbling block
σκάνδαλον (skandalon)
stumbling-block, cause for error.

ℭ𝔳𝔠𝔨𝔱𝔥𝔬𝔩𝔦𝔠𝔦𝔰𝔪