I have listened from someone that we should not cut our nails on Wednesday because it can cause some kind of disease (I do not remember the name of that disease). Is it right ?
Cutting nails per se is sunnah and there's no sound backup neither for a recommendation for doing it on a special day of the week (be it Friday or Thursday) nor an advise for leaving it on a special day of the week (be it Wednesday or any other day). So you may cut them on any day of the week.
"Five practices are characteristics of the Fitra: circumcision, shaving the pubic hair, cutting the moustaches short, clipping the nails, and depilating the hair of the armpits." (See for example in Sahih al-Bukhari)
Ten are the acts according to fitra: clipping the moustache, letting the beard grow, using the tooth-stick, snuffing water in the nose, cutting the nails, washing the finger joints, plucking the hair under the armpits, shaving the pubes and cleaning one's private parts with water. The narrator said: I have forgotten the tenth, but it may have been rinsing the mouth. (See for example in Sahih Muslim)
Nevertheless some madhhabs have recommended certain days for cutting nails:
The Hanafis, Malikis and Hanbalis have recommended it each Friday, but the Hanafi's said it is recommended after the prayer (Friday prayer), while Hanbalis recommended to do it before noon (before the prayer). Another recommendation of the Hanabli's is each Thursday, and this was also the view of Sufyan a-Thawri. The Hanablis also said one could choose when to do it.
Imam an-Nawawi (Shafi'i) said it depends on the nails some people have nails that grow faster than others so some people may need to cut their nails even more often than others.
The soundest among the narrations and evidences of the scholars is one of imam al-Bayhaqi in his as-Sunan al-Kubra saying that 'Abdullah ibn 'Omar used to cut his nails and moustaches on Friday. Imam al-Bukhari only compiled a rather weak narration in his al-Adab al-Mufrad -see here- supporting the recommendation of Thursday's.
Some sources -all in Arabic-:
- In this fatwa islamweb #69374 people ask whether cutting nails on Wednesdays is permissible or does it cause poverty: The answer is cutting nails is a sunnah and not restricted on a special day.
- In this fatwa islamweb #2047 it was asked whether cutting nails on Friday is sunnah and whether there's an evidence for that: The answer says it is sunnah to cut nails and jumua'h might be a good reason to do it, but its not an exclusive day for that.
- In this fatwa islamqa #118891 it was asked whether the Prophet () used to cut his nails each Friday and in the answer the Mufti denied the existence of any sound narration saying that Muhammad actually said or did so.
- This article is a nice overview on rulings and fiqh opinions and their evidences on the topic of cutting nails.