A blessing before a meal was common for Jews, but looking up to heaven while doing so was not. Jesus only did this just before a miracle (see Mark 7:34; John 11:41).
He looked up to his Father in heaven, who had sent him into the world as Mediator (John 11:41–42), and who accomplished his work on earth through him (John 4:34; John 5:36; John 10:30). This shows that all must come from God. In communion with the Father, Jesus pronounced blessing over the bread (Matthew 26:26). His blessing miraculously increased the bread.
While the blessing prior to a meal was common practice among the Jews, the act of looking up to heaven while doing so was not. Jesus also only did this on a few occasions, and every time he did so an exceptional act followed (see Mark 7:34; John 11:41).1
He looks up to heaven, where his Father dwells—the Father who sent him into the world as Mediator (John 11:41–42), and who accomplishes his work on earth through him (John 4:34; John 5:36; John 10:30). In this we see that everything must come—and does come—from God. In communion with the Father, Jesus himself pronounced a blessing over the bread (Matthew 26:26). Through the Lord’s blessing, the bread is supernaturally increased.2
19 Il fit asseoir la foule sur l'herbe, prit les cinq pains et les deux poissons, et, levant les yeux vers le ciel, il rendit grâces. Puis, il rompit les pains et les donna aux disciples, qui les distribuèrent à la foule.