What doubtful (unclear) things should be avoided?

Narrated Anas:

The Prophet ﷺ passed by a fallen date and said, "Were it not for my doubt that this might have been given in charity, I would have eaten it." And narrated Abu Huraira the Prophet ﷺ said, "I found a date-fruit fallen on my bed."

حَدَّثَنَا قَبِيصَةُ، حَدَّثَنَا سُفْيَانُ، عَنْ مَنْصُورٍ، عَنْ طَلْحَةَ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ مَرَّ النَّبِيُّ ﷺ بِتَمْرَةٍ مَسْقُوطَةٍ فَقَالَ " لَوْلاَ أَنْ تَكُونَ صَدَقَةً لأَكَلْتُهَا ". وَقَالَ هَمَّامٌ عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ عَنِ النَّبِيِّ ﷺ قَالَ " أَجِدُ تَمْرَةً سَاقِطَةً عَلَى فِرَاشِي ".