Divrei Yechezkail: Vayigash II
“Now I can die because I have seen your face.” How could Jacob speak of death on such a joyous occasion? There is no question that if Jacob said Shema when he saw that his family was reunified and could celebrate the Unity of God with a fresh heart that he immediately followed with Tefillah – A person should always immediately follow the final blessing of the Shema – Redemption – with Tefillah.
What did Jacob do when he finished his prayer? The Baal Shem Tov taught that one should never say Tachanun, offering his life for God, if he feels lacking in an important way.
Jacob could not say Tachanun all the years that Joseph was gone because he felt that he had failed in some significant manner. Once he saw Joseph he could recite Tachanun, “I will die,” I am willing to die for You. Jacob was reciting Tachanun.
(Divrei Yechezkail HaChadash, Sichot Yekarim, #27)