Translation:

10. And spend something (in charity) out of the substance which We have bestowed on you before death should come to any of you and he should say "O my Lord! why didst thou not give me respite for a little while? I should then have given (largely) in charity and I should have been one of the doers of good."

Notes (Tafseer)

5477. "Substance" or "Sustenance". Whatever good we enjoy comes from Allah, and it is our duty to use some of it in the service of others, for that is Charity and the service of Allah. Every unselfish act is Charity. And we must not postpone our good resolutions to the future. Death may come suddenly on us, and we cannot then be allowed to plead for more time. Every present moment calls urgently for its good deed.