Upvote:1
In 2 Samuel 20:23, David and Bathsheba's first son together died, because of David's sin with Bathsheba and murder of her husband. David says
v.23 " ... I will go to him one day, but he cannot return to me.” 2 Samuel 20
So David, a man after God's own heart, knew his infant child would be in heaven.
Upvote:2
See John Piper's article: What happens to infants who die?
All infants are sinners (Romans 5:12-21)
"At least" Some infants are saved: John the Baptist (Luke 1:15), David (Psalm 22:9-10).
Those not capable of perceiving good and evil are not guilty of sinful acts (John 9:41, Romans 1:20).
God is good (Psalm 119:68). Trust that he will do what is just and merciful.
Quoting Piper:
It should also be emphasized that the salvation of all who die in infancy is not inconsistent with unconditional election (the view that God chooses whom to save of His own will, apart from anything in the individual). As Spurgeon pointed out, it is not that God chooses someone to salvation because they are going to die in infancy. Rather, He has ordained that only those who have been chosen for salvation will be allowed to die in infancy. God's justice in condemnation will be most clearly seen by allowing those who will not be saved to demonstrate their inherent sinfulness through willful, knowing transgression.