הָרִֽאשֹׁנוֹת֙ מֵאָ֣ז הִגַּ֔דְתִּי וּמִפִּ֥י יָצְא֖וּ וְאַשְׁמִיעֵ֑ם פִּתְאֹ֥ם עָשִׂ֖יתִי וַתָּבֹֽאנָה׃
여호와께서 가라사대 내가 옛적에 장래사를 고하였고 내 입에서 내어 보였고 내가 홀연히 그 일을 행하여 이루었느니라
Mekhilta DeRabbi Yishmael
"upon your hand": This is the left hand. You say this, but perhaps it is the right? Though there is no proof for this, it is intimated in (Isaiah 48:3) "My hand has also founded on earth, and My right hand has spanned the heavens," and (Judges 5:26) "Her hand reached for the tent pin, her right for the workmen's hammer," indicating that "hand," unqualified, is the left hand.