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" رشوه "(Bribe) is an Arabic word from the root letters of "ر ش و" and is pronounced in three different ways, rishwah, rashwah and roshwah. Rishwah is single form and it's plural form is "رُشا" or "رِشا" which means ‘wage’ in Farsi. This term refers to achieving a goal through conspiracy and paying something.
The Maraje have used all four sources of Islamic law (The Quran, the sunnah, Ijma'a and the intellect) to forbid bribing.
1- The Holy Quran:
In the Quran the Almighty says: " And do not eat up your property among yourselves for vanities, nor use it as bait for the judges, with intent that ye may eat up wrongfully and knowingly a little of (other people's) property " Allamah Tabatabei says in Tafisr Al-Mizan: "الادلاء means to send down carrier pail to get water from a well and what is meant by this term in this verse is the bribing of rulers. The verse carries a very nice metaphor, saying that the bribe giver is analogous to the water at the bottom of a well which is pulled out of the well through the pail of bribery." Thus, the forbiddance of giving bribes entails the forbiddance of receiving them.
2- The Ahadith:
Many Ahadith have mentioned getting bribes as one of the instances of Kufr (the state of disbelieving). For example there is hadith by the prophet that says: "Keep yourselves away from bribes because it is kufr and one who receives them will never smell the scent of paradise".
The Ijma'a and consensus of all Muslim sects on the issue is another reason that support's this opinion.
4- The intellect:
Bribing can cause several problems for society. When a certain group of people can reach their goals through bribing others, then the majority of people will face difficulties in getting their rights. When the authorities get used to getting bribes they will no longer treat others who do not pay them money as they should and this will cause serious problems and corruption in the government and it's departments. Therefore some Muslim scholars like Moqaddas Ardabili have referred to the intellect as an independent reason for proving the forbiddance of receiving bribes. In his book "Majma’ul-Faidah wal-Burhan" he says: "We conclude the prohibition of rishwah from to the intellect, the Quran, the sunnah and the Ijma’ of all Muslim sects."
In the end, we will list the Fatawas (verdicts) of contemporary marja’s:
Grand Ayatollahs Khomeini, Khamenei, Safi, Fazel, Makarem and Noori: Paying money to those who work in offices and departments (that have been hired to be at the service of the people) will cause corruption and is haram. Receiving bribes is also haram for the one who receives it and he does not have the right to use it in any way (because it doesn’t belong to him).
Grand Ayatollahs Tabrizi, Sistani and Vahid: Bribing is haram unless one has no choice but to do so to get his/her right, but receiving bribes is haram for one who is paid to do work for others.
Majma’ul-Bahrayn, vol. 1, pg. 184.
Ibn Athir, Al-Nihayah, vol. 2, pg. 226.
Khui, Misbahul-Fiqahah, vol. 1, pg. 256.
Al-Mizan, vol. 2, pg. 52, under verse 188 of surah Baqarah.
Misbahul-Fiqahah, vol. 1, pg. 234.
Wasa’el, vol. 12, pg. 63, chapter 5, hadith 1
 Najafi, Jawahirul-Kalam ri Sharh Shara’ul-Islam, vol. 22, pg. 145; Misbahul-Fiqahah, vol. 1, pg. 263.
 Muqaddas Ardebili, Majma’ul-Fa’idah wal-Burhan fi Sharh Irshadil-Adhan, vol. 12, pg. 49.
 Imam Khomeini, Tahrirul-Wasilah, vol. 2, chapter of judgment, issue 6; Ayatullah Fazel, Jame’ul-Masa’el, vol. 1, question 972; Ayatullah Makarem, Istifta’at, vol. 2, question 664 and 665; Ayatullah Safi, Jame’ul-Ahkam, vol. 2, question 1540; Ayatullah Khamenei, Ajwibatul-Istifta’at, question 1246 and 1247; Ayatullah Bahjat, Tawdihul-Masa’el, chapter of unrelated issues, issue 16.
 Ayatullah Tabrizi, Istifta’at, question 999; Ayatullah Vahid, Minhajul-Salehin, vol. 3, issue 32; Ayatullah Sistani, Sistani.org and with help from the Porseman software.