As far as man goes:
There is a way which seemeth right unto a man, but the end thereof are the ways of death. - Proverbs 14:12
As it is written, There is none righteous, no not one: - Romans 3:10
That is why He gave us His word and a conscience with His law written in it (Romans 2:14-15). As far as God goes:
Genesis 9:6 Whoso sheddeth man's blood, by man shall his blood be shed: for in the image of God made he man.
Exodus 12:13 Thou shalt not kill.
Proverbs 6:16-17 These ... things doth the Lord hate: ...A proud look, a lying tongue, and hands that shed innocent blood ...
Revelation 21:8 Murderers ... shall have their part in the lake which burneth with fire and brimstone: which is the second death.
Some OT, some NT. He came to fulfil the Law. Now we have a New Covenant. Whether it supersedes or perfects the old seems to be still under debate, but the fact is we have a lot of trouble knowing what to do in many circumstances. The Hippocratic Oath is ancient, but still a guideline. What is the harm feeding a helpless person?