Greetings, charity, and the Hereafter

What is the main point of «بَقِيَ كُلُّهَا غَيْرَ كَتِفِهَا»?

Greetings, Family Ties, Charity, and Preparation for the Hereafter (Accounts 6–8)

• The meat physically returned
• Keeping food at home became forbidden
• Charity can retain lasting reward
• The shoulder is inedible