First of all, we’d like to state that one of the main duties upon man is to show kindness towards his parents because Allah the Almighty says: “Thy Lord has decreed, that you worship none save Him, and (that you show) kindness to parents. If one of them or both of them attain old age with thee, say not ‘Fie’ unto them nor repulse them, but speak unto them a gracious word.” (Al-Isra’: 23)
One should show all kinds of good treatment to one’s parents. Ibn `Abbas (may Allah be pleased with him) reported that the Prophet (peace and blessings be upon him) was once asked about the best deeds: “The Messenger of Allah (peace and blessings be upon him) says, ‘Having faith in Allah and His Messenger, then honoring one’s parents.” (Reported by Al-Bukhari and Muslim)
Obeying and honoring one’s parents is a means of entering Paradise. Abu Hurayrah (may Allah be pleased with him) quoted the Prophet (peace and blessings be upon him) as saying: “He is doomed, he is doomed, he is doomed.” Then someone said, “Who, O Messenger of Allah?” He said, “The person whose parents, one or both of them, reach old age during his lifetime but he does not enter Paradise .” (Reported by Muslim)

The eminent Muslim scholar and renowned Da`iyah, Sheikh `Abdel Khaliq Hasan Ash-Shareef, states:

“It depends on whether the children who happen to be the givers in this case are well-to-do owning huge properties, or they are only able to fulfil their needs and have a small sum of money to be used in difficult circumstances or they are not able as they have no extra money above your needs.

It also depends on whether the parents need that money for a necessary need or a complementary need.

Suppose they asked to give them a small sum of money while the children are well-to-do and have millions. In that case, they have to give them. But suppose that they asked to give them a big sum of money while the parents themselves are not in need and this is the only money the children have, then it is not their right to ask for that money leaving their adult children in a difficult situation.

So, the issue depends on the giver’s financial state and the parents’ need for that money.