"And We had already made a covenant with Adam before," meaning: what he was commanded to do, which was not to eat from the tree. "But he forgot," meaning: he neglected what he was commanded to do. "And We found no determination in him," meaning: patience.
﴿وَلَقَدْ عَهِدْنَا إِلَى آدَمَ مِنْ قبل﴾ يَعْنِي: مَا أُمِرَ بِهِ: أَلَا يَأْكُل من الشَّجَرَة ﴿فنسي﴾ يَعْنِي: فَتَرَكَ مَا أُمِرَ بِهِ. ﴿وَلم نجد لَهُ عزما﴾ أَي: صبرا.