{α : Sort u_1} →
  {β : Sort u_2} →
    {motive : (α ↪ β) → Sort u} →
      (t : α ↪ β) →
        ((toFun : α → β) → (inj' : Function.Injective toFun) → motive { toFun := toFun, inj' := inj' }) → motive t