《隋书·列传·卷十》
起初，长孙长宁王生后，我同皇后一同抱养他，杨勇自己心存芥蒂，连续派人来要回去。
初，长宁诞育，朕与皇后共抱养之，自怀彼此，连遣来索。
In the beginning, when my oldest grandson Changning was born, the empress and I raised him together. Yang Yong held a grudge against this and sent people to demand his return.