What is the four-letter idiom that means I received help from others when I was in the most difficult time?

Send charcoal in the snow xuě zhōng sòng tàn

[Definition] Send charcoal to people to keep warm on snowy days. It is a metaphor for giving material or spiritual help to others when they are in urgent need.

[Quote] Fan Chengda of the Song Dynasty "Sending Charcoal and Mustard Hidden in Heavy Snow": "It is not necessary to send charcoal in the snow; talking about pretending to be a scenery requires poetry."

[Correct pronunciation ] Send; cannot be pronounced as "shònɡ".

[Antonym] To add insult to injury, to throw stones into the well

[Usage] Used as a compliment. It is a metaphor for giving timely help to others when they are in trouble. Generally used as predicate, object and attributive.

[Structure] More formal.

[Example] He explained the optimization method to the workers in a simple and easy-to-understand way; the workers felt as if the breeze was blowing on their faces; the stream was gurgling; it was connected with the actual production; and they received ~ results.