Mk 6:50: ἐγώ εἰμι, "[It] is I", or, more literally, "I am"
Ex 3:14 LXX: ᾿Εγώ εἰμι ὁ ὤν, "I am who I am". . . . ῾Ο ὢν, "I am"
Ex 3:14: אֶֽהְיֶ֖ה אֲשֶׁ֣ר אֶֽהְיֶ֑ה, "I am who I am". . . . אֶֽהְיֶ֖ה, "I am"
Ex 3:14 LXX (NETS): "And God said to Moyses, 'I am The One Who Is.' And he said, 'Thus shall you say to the sons of Israel, "The One Who Is has sent me to you".'"