Showing how Matthew 27:46 indeed references the beginning of Psalm 22:1
‘…”My God, my God, why have you forsaken me?”…’
(Psalm 22:1 NIV)
– however the recitation of the Psalm stops there, and the actual context of what is being communicated is found in Isaiah 49:4
‘…“I have labored in vain;… yet surely my right is with the LORD, and my recompense with my God.”’
(Isaiah 49:4 ESV)
– As only part of the people believed, Isaiah says ‘…laboured in vain…’ (ESV), and this communicates how Christ yearns for all people to be saved, and not just some – much like His Father’s will (1 Timothy 2:3-4, 2 Peter 3:9).
Isaiah also shows us how Christ (Messiah) also looked forward to being at the right hand of G-d above, again.