Praise be to Allah.
Concealing voluntary charity is better than giving it openly. It was narrated that Abu Hurayrah (may Allah be pleased with him) said: The Prophet (blessings and peace of Allah be upon him) said: “There are seven whom Allah will shade with His shade on the Day when there is no shade but His… a man who gives charity and conceals it so that his left hand does not know what his right hand is giving.” Narrated by al-Bukhaari (1334) and Muslim (1712).
This description refers to going to great lengths to conceal charity. But giving charity openly may serve an interest sometimes, such as making others follow one’s example.
For more information, please see the answer to question no. 145557
If a man gives charity from his own wealth but says to another person, This is from So and so, this is a lie, and lying is haraam.
If he wants to conceal the matter so that no one knows about this charity, there is nothing wrong with double entendres and using oblique words if there is a need for that.
So for example he may say: “This is not my money,” meaning that it belongs to Allah.
Or he may say: “This money is from someone who wants to give it in charity,” meaning himself, and other phrases that are true but serve the purpose of concealing the charity.