Does Islam forbid buying from auctions? Suppose someone is indebted to another and not able to repay, and runs away to another land, his property is auctioned to recover the debt, if I buy from that auction have I committed a sin?

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Purchasing from an auction is permissible as long as the transaction does not contain any Haram. The evidence for its permissibility is the Hadith reported from Anas Bin Malik in Sunan Abu Dawood and al-Tirmizi that "a person came to the Prophet (Sallallahu Alaihi wa Sallam) begging from him. He asked: "Have you nothing in your house?" He replied: 'Yes', a piece of cloth, a part of which we wear and the other part of it we use as mat, and a wooden bowl from which we drink water'. The Prophet (Sallallahu Alaihi wa Sallam) said: "Bring them to me". He then brought these articles to him and he (the Prophet (Sallallahu Alaihi wa Sallam) took them in his hands and asked: "Who will buy these?" A man said: 'I shall buy them for one Dirham'. Then the Prophet (Sallallahu Alaihi wa Sallam) asked twice or thrice: "Who will offer more than one Dirham?" A man said: 'I shall buy them for two Dirhams', … etc" .
Allah knows best.