In verse 80, it was said: فَلَمَّا اسْتَيْأَسُوا مِنْهُ خَلَصُوا نَجِيًّا (So when they lost hope in him, they went aside for consultation).
After that, the primary statement of the oldest brother which begins with the words: قَالَ كَبِيرُهُمْ (The oldest of them said) is continued till the end of verse 80. The statement was: "Do you not know that your father had taken pledge from you in the name of Allah, while you had defaulted earlier in the case of Yusuf (علیہ السلام) . So, I shall never leave this land unless my father permits me (to return) or Allah decides about me. And He is the best of all judges."
This is the statement of the oldest brother. Some commentators identify him as being Yahuda (Judah) - and he was, though not the oldest in age, but was certainly the eldest in knowledge and merit. Other commentators say that he is Ruebel (Rueben) who is the oldest in age and he was the one who had suggested that Sayyidna Yusuf (علیہ السلام) should not be killed. Still others have said that this oldest brother was Sham un who was known to be the eldest in power and rank.