Is it permissible to say "Masha'Allah" upon seeing a beautiful dog, believing that it is from the creation of God, especially after one of the neighbors denied the permissibility of doing so?

It is recommended to say: "Whatever Allah wills, there is no power except with Allah" (Mā shāʾa Allāh lā quwwata illā billāh) for anyone who is pleased with something from their wealth or offspring, based on the noble verse: ﴿And why did you not, when you entered your garden, say, 'Whatever Allah wills, there is no power except with Allah'?﴾ [Al-Kahf:39].

Furthermore, this remembrance is prescribed when one sees something admirable among Allah's creatures or concerning others, out of fear of envy, due to the general saying of the Prophet, peace and blessings be upon him: "If one of you sees something in himself or his brother that he admires, let him supplicate for blessings, for the evil eye is real." If the questioner intended by this saying to prevent envy for what he saw in the dog, then his saying "Whatever Allah wills, there is no power except with Allah" is prescribed, especially if the dog is one whose keeping is permissible.

However, if the intention is to express wonder at Allah Almighty's creation and to reflect upon it, then what is prescribed is to glorify Allah, remember Him, and supplicate to Him, as in His saying: ﴿And they give thought to the creation of the heavens and the earth, [saying], "Our Lord, You did not create this in vain; exalted are You [above such a thing]; then protect us from the punishment of the Fire."﴾ [Al-Imran:191].