What he feared after Uhud, and what he did not
He had just prayed over the dead.
وَإِنِّي وَاللَّهِ مَا أَخَافُ عَلَيْكُمْ أَنْ تُشْرِكُوا بَعْدِي، وَلَكِنِّي أَخَافُ عَلَيْكُمْ أَنْ تَنَافَسُوا فِيهَا
Wa innī wa-Llāhi mā akhāfu ʿalaykum an tushrikū baʿdī, wa lākinnī akhāfu ʿalaykum an tanāfasū fīhā
“By Allah, I do not fear that you will associate others with Allah after me. But I fear that you will compete with one another over it.”
Where this comes from
He prayed over the dead of Uhud, then went to the pulpit and said he was their predecessor and a witness over them, and that he was looking at his Basin at that moment, and that he had been given the keys of the treasures of the earth.
The full narration
Narrated `Uqba bin 'Amir:The Prophet (ﷺ) went out and offered the funeral prayer for the martyrs of the (battle of) Uhud and then ascended the pulpit and said, "I am your predecessor and I am a witness against you. By Allah, I am now looking at my Tank-lake (Al-Kauthar) and I have been given the keys of the treasures of the earth (or the keys of the earth). By Allah! I am not afraid that after me you will worship others besides Allah, but I am afraid that you will start competing for (the pleasures of) this world
Source
Ṣaḥīḥ al-Bukhārī · 6426
- Agreed upon as authentic (al-Bukhārī / Muslim)